Originally Posted by Naji Assan
Best way to justify the costume would be if he stays with the X-Men in the 70s after the timeline is reset. He'll need a suit and given that the First Class suits were yellow and blue, it would actually match the team.
I think the only problem with that, and I forget where I read this, but the timeline doesn't reset until he goes back to the future. So, if he stayed in the 70s, the whole point of him travelling back would be lost.
But then again, I suppose he could always go back a second time. Which will probably happen, as I believe whatever he does might lead to a darker future.