It doesn't matter what some guy posts on some message board (unless it's a threat, an incitement of violence, or something along those lines). It doesn't matter if he says he believes in "Gorean philosophy," whatever the hell that is.
What matters are his actions. If he's treating women disrespectfully then, by all means, throw him out. But he's allowed to believe whatever the hell he wants, and the idea that he should face repercussions for his beliefs is wrong, whatever age he was when he came to those beliefs.
Sure, there's going to be some correlation between holding misogynistic beliefs and inappropriate behavior toward women, but we don't punish the beliefs, we just punish the behavior. That's what makes this a free society.