I also think it's legal trouble. While I really don't think he's a criminal or whatever, I'm thinking it's some kind of eligibility issue.
Ditto on Constannoying. Ditto on AI's version of the Bash Brothers, period. I have to admit that I haven't been keeping up with this season as much as previous ones, but I will say that Mario was my favorite from the beginning, and the only one I really paid attention to.
Perhaps Mario withdrew before he was "outed" by the media? It's weird how NO ONE's saying anything about the situation.