Considering Inti said the complete opposite in this summary, it never crossed their mind. Rather, the opposite, Sigma Virus countermeasures in X, who's the originator of the suffering circuit. Of course, there's a lot to say for the fact that other Repliroids lack these countermeasures, and have a less than perfect suffering circuit.
That's contemporary conjecture, not from the standpoint of the times. The virus turning Zero good was a radical and unheard of idea in 2006. When you're talking about the virus turning Zero good back then, it could just as easily become a Suffering Circuit program "virus" leaking from X's capsule that spread to Zero and infected him. The use of the suffering circuit to make reploids question whether either side is truly right or wrong is exactly the kind of thing that could turn a bad violent dude into a thoughtful justice-driven guy. But this was dismissed by us back then because we dismissed the premise, that the virus turned Zero good. Up until last week or so, we were still rejecting it.
Now we're told in an official capacity that Zero was turned good by the virus. We have other call to dismiss that particular aspect of suffering circuit's role as a direction that was not followed, but we can not say that years before MM10 was around that Inti was not thinking of taking things in that vein. The idea that the suffering circuit is in some way part of X's perfect virus counter-measure is itself still conjecture at this point.
But see, by bringing to light what the Hunters knew prior to X6, you only establish what Inti is not talking about. For them to reference the Nightmare incident, and not Eurasia (which is already mentioned in this timeline, not to mention a major contributor to the storyline of Z4), says that something beyond what the Hunters had established in X5 came to light.
The passage in the timeline seemed to already lay it out for us. The conditions were these:
“The Nightmare Incident” occurs, an event where a subspecies of the Sigma Virus that attracts attention as the Nightmare Virus spreads throughout the world. The fact was proven that Zero was it source, as he was a carrier of the Sigma Virus, and was contagious to his surroundings as he worked across the world as a Hunter.
Zero as the source of the Nightmare was expressed first by Isoc to the entire world, then confirmed by Gate himself to the Hunters. Zero was known to be a Sigma virus carrier by the end of X5, but Zero refused to get fully checked out at that time, instead pressing on until the battle with Sigma was settled, and subsequently disappeared for the weeks leading directly into X6. The last issue, that Zero is contagious to his environs, is the only precursor that we might be able to toy with. Even though they knew Zero had the Sigma virus in him and was the basis for the Nightmare, it does not necessarily lend itself to believing that Zero is contaminating the world around him. It is a logical conjecture based on the first two points, and one would think it was an important question that they would want to be answered, but maybe somehow they missed this key point which is perhaps the most damning to Zero's condition. Zero himself seemed to recognize the danger his very existence presented in his X5 ending where he discovers the meaning of his dreams, but perhaps he's forgotten that information post his revival. Certainly no one treats Zero as though he's hazardous and constantly spreading a deadly virus in X7~on. Perhaps they do not recognize this yet, and the X series will continue until they do. I believe that is currently the best shot for keeping X7, X8, and to a more difficult extent XCM in the timeline. But that's all from searching for a loophole that would serve my hypothesis and refusing to accept the face value of the new information given.
The reason for retcon is to cancel out contradictions, that doesn't mean we as fans have to go about and make those contradictions ourselves. Only when things are absolutely written into a corner is retcon a mandatory answer. As long as we can reason our way out of that corner, then we should do so, and not invoke the name of retcon. Bringing up retcon here is just a cop-out excuse for angry gamers to vent their frustrations at the course a story has taken with its elements.
A retcon is usually the cause of the contradiction that it is supposedly canceling out, so far as I can tell. Capcom and Inti have yet to write a manifesto that guarantees they feel the same way about retcons as you do. The fans weren't the ones who wrote the Zero Collection's page to read the way it does. Inti did not have to group Zero's sealing with the Nightmare Incident in their timeline, nor mention it again in X's bio. But they did. And to be fair, the idea they are either purposefully or accidentally presenting there should be explored rather than outright denied.
If it makes you feel better, don't call it a retcon. Ask whether they ever actually said that X7 and on were part of the Zero timeline before, or whether we only assumed they were. If they didn't state that earlier, then call it a "late reveal" or however you excuse it to yourself.
Rockman Perfect Memories posed the question of how Zero could be sealed in his X6 ending and still appear in X7. It also asked when and how Zero's 100 year sleep (now perhaps reduced to 50) would be applied, which allowed us our leeway to believe that this particular ending would occur at a later occasion at the ending of the X series. The book also said the key to putting things together would be found in X7 when it came out. But X7 was still in development at the time, and wouldn't release for over half a year later.
Perhaps that plan also changed since then, because when it did come out, X7 just made it that much more confusing. It did not say anything directly about Zero's sealing. It gave some cryptic references to be interpreted, like Zero's ending where he dreams of X trying to eliminate him, or Anteator's bizarre "memories of the future/false images of the past" comments that sounded reminiscent to the concepts in the Zero series. It also mirrored Zero 2's intro boss, with how in both stages Zero is forced to battle a giant scorpion mechaniloid. Can we say we understand what message was being sent there? Does Zero's data somehow contain prophetic glimpses into the future, or does Zero dream of the events of a parallel world?
Then came the Compendium of Rockman X, which repeats that the Zero series is thought to follow the 100 year sleep ending of X6, and yet marks the event with a "?" on Zero's personal record between X6 and X7. Not much better for clarity's sake. Is the question mark denoting that it takes place at an uncertain later time, or that the event may or may not take place at all, as in a branching timeline event?
And then we have MXOCW's comment that Capcom artist Higurashi thought that the Zero series was taking place in 22XX, while he was working on Command Mission. Apparently in a parallel world sort of way, since there's not much leeway for Z1 to take place in 22XX if the 100 year seal took place after Command Mission. Was he just really confused about things, or was his thinking based on the already known to him premise that Zero and Command Mission are separate timelines?
Not that it in any way proves or disproves the point, but split timeline theories have been pretty popular among Japanese fans for years (as fan sites like
this and
this demonstrate). After shuffling through a few Japanese blog reactions to the Zero Collection site, they're having more trouble with accepting things the virus coming from Zero's capsule and turning Zero good, Ciel needing her visor to interact with Cyber Elves, and the Big 4 being parts recent reincarnations of X's partitioned soul than they are dealing with the snubbing of the late X series. Perhaps it's time we unlearn what we have learned and examine why we're trying to prove their connectedness in the first place.
But if they did that here, then to what end? As a matter of pattern recognition I just don't see breaking from X6 as something Inticreates would do. As off-the-wall as their storytelling gets, they enjoy throwing obscure references out there, such as B&C and RM&FWS. They worked hard towards maintaining Legends as the eventual future without writing themselves into a corne.
We're talking about the same Inti that created a timeline split right off the bat for ZX? Vent>Ashe/Aile>Grey's parallel worlds divulged and continued simultaneously into the future, and they don't seem to bothered--they'll get to Legends either way (and perhaps when you're dealing with a connection that's thousands of years separated, the only way they could really "mess up" the Legends bridge is if they blow up the entire Earth Alderaan style, but there might even be workarounds to that). We already know that not every obscure reference is one of canonical relevance. It just puts the obscure references to X7 and such at the same level as the references they made to the EXE series.
X7, X8, XCM would still be canonical to themselves and each other, and X1-6 could continue to be canonical to both X7+ and Zero+. What it would do is allow the X series to write itself a new future, take things in a completely different story direction (which is something they have been doing already, but here could do so without a timetable or future prerequisite to stay within). They can rebuild the world differently than how it happens in the Zero series. They never have to have an Elf War at all, technology can branch out in different ways (like Force Metal and Copy Chips). They could even kill off X or Zero--for real this time!--if they so wanted. Axl doesn't have to disappear. The X series can go on for centuries, perhaps eventually arriving at Legends in its own way, perhaps not. The X series would be free.
To a really push the envelope, perhaps the history and events of the Zero series don't even have to be the same as the history of the X series. By that I mean, perhaps in the Zero series timeline Zero was spreading the virus contagiously, while perhaps in the X series version he isn't. Perhaps while in the Zero universe, Zero was infected from his own capsule by some ancient stowaway virus, while in the X universe Wily put the virus into him on purpose. I don't actually want to push things that far and make them that complicated, but it would be another potential option for the removal of certain contradictions with past books that we've been given over to. Only, the mess it would make in figuring out what is canon to what series would probably always boil down to "we just don't know for sure, look at it how you want." But there's a fanon element to everything we're doing. If we could create the canon, we'd be Capcom. Instead we just view it and ponder.