I SINCERELY doubt that. Even assuming the post is true, the conception of a character does not equate to their final place in the storyline. All context suggests that Depth Dragoon is a Maverick Hunter under Redips' command (he refers to X and co. as traitors, and his body survives the traditional boss explosion, which implies that X and co. made it a point to spare his life).
Ninetales is grouped together with Rafflesian and Duckbill Mole in one of the Rec Room posters. It's not much, but it's about all we have, seeings how none of the secret bosses are mentioned in the texts of the Rec Room's data files.
See, I can buy Rafflesian, but how you can create Ninetales and not have him in the "High Performance" class kinda baffles me. I guess in theory he could just be ramped up on Supra Force Metal, but still.
I think it's safe to say that Ninetales is more powerful in gameplay than he is supposed to be by storyline. If memory serves, I believe one of the NPCs mentions that he is a "prisoner" of the Resistance. And really, I don't see the likes of him being captured that easily. Plus, you know, the whole "SFM Redips is god and is the only thing to ever take X, Zero, and Axl head-on and have all three on the ropes" thing.