[He fully recognizes that this is kind of a Big Deal for her, so he'll try to expand on it a little.]

To be honest, I don't know all of the details, but from what I've heard, he's changed a lot. He's not a terrorist anymore, and he's actually trying to help mutants without hurting humans at the same time. Things were bad for a while, really bad, but... he must have done something to earn their trust.