The question is not whether getting banned on Xbox would ban you from all the games or not, the question is whether Xbox should be able to ban you entirely.
That's the problem. They shouldn't be able to own the platform. There should be no platform for them to own to begin with. They shouldn't have the power to ban anyone nor should there be any place to be banned from.
You're gonna speak of moral obligations while defending DRM'd platforms owned by copyright monopolists? You gotta be kidding me.