The problem here is less that he's an RL rapist (though that is a huge problem) and more that he continues to play out underage sex and underage rape with people who are not aware of his past, some of whom are survivors themselves.

The facts are that he admitted it, that no one has a "right" to RP, and even if they do, whose rights are you advocating here: the rights of the survivors to not have to play uninformed with someone who has admitted to rape, or the rights of someone who admitted to rape to play with others without informing them?

If they absolutely do not want to ban him, they should at least put up fair warning for what people are getting into. We're not talking about weird kinks, flakiness, or PAness here. We're talking actual RL crimes.