Interesting.... I can remember quite a few , brace your self, long, deep debates here. Its all about how civil people act and as far as the internet goes, this place is a port in the storm. If people discuss with cool, calm heads we can have great conversations here. Its just that most of the time someone gets offended that not every one agrees that they are correct and every one else is wrong.
I do know of one person who got frustrated about not being allowed to discuss various things. Presumably they were deemed too 'mature' for our audiences, despite them being scientific/medical rather than erotic or whatever. I only remember this in general terms, though.
As far as I am aware, he was not banned. He chose to leave. Since people who aren't here can't speak for themselves, I thought I'd mention this. However, its worth noting that he was/is something of an exception.