There’s no in-story reason, obviously. Maybe Hickman should’ve tried to write one but for now, it sis entirely driven by her fame and the need for drama. That’s why I think that Xavier isn’t playing her, he’s really just being written like an idiot.
Edit: My mistake. I thought you were asking about being on the QC, not Krakoa. Yeah, everyone can come to Krakoa. I think the parts where they’re using her and giving her power is wrong.