I wouldn't be so quick to dismiss it. He's not just some nobody exactly, his name does appear in the credits of the game, even though it's nothing to do with the programming or making of it. Being part of the company does give him a unique vantage point to have been informed or discovered whatever this secret is. And I have no problem believing that there is still something about the game we have yet to discover. Or even many somethings.
That said, I greatly doubt that this secret he has in mind is anything earth-shatteringly amazing. I don't expect a secret boss or new mode or amazing contra code that gives you items during time attack runs. I'm thinking this thing is probably something small along the lines of "Oh, hey, that's a kinda neat little easter egg there."