Board Thread:Sonic News and Updates/@comment-29621263-20160814061718/@comment-477304-20161019225014

How do you know it's non-canon? Why is there additional dialogue for Metal Sonic if that's the case?

That's an ability that's he's only ever displayed in his Neo Metal Sonic form, even if he had it, what reason does he have to transform into his classic self? I have no idea what you're saying in this second point.

Both your third and fourth points can be addressed Eggman's interference in the timeline, which was presumably restored at the end of the game.