First, your right nobody does own mars and based on one of the only UNANIMOUS decisions by the United nobody is ever allowed to. It is preserved like the moon “for all mankind”
It’s a thing lawyers bring up whenever Elon Musk talks about colonizing mars. He legally can’t, for real he just can’t. It’s against a law that everyone on earth agreed to.
Secondly yeah they were totally forced there. Yeah the arrako mutants agreed to it, but that’s how empires work. You make the slave happy with his enslavement, then they never question it. And krakoa has to civilize all those filthy mutants who spent generations fighting an awful war that the X-men know nothing about and do not care about. “You were not there!”
As for magneto, he proclaimed himself a god in the middle of Jerusalem I don’t think he or his current writers care anymore about that side of his character