Your thread title is incorrect. It looks like he wasn't cut for using the r-word but for not apologizing.
I can see both sides of the r-word thing. On the one hand I understand why people with that congenital condition (or more typically their family members) are offended by r-word variations being used as a insults or pejoratives. On the other hand, we apparently can still use the word dumb as an insult or a pejorative, and we don't have to refer to it as the d-word. Though I think most people would intuitively feel that at the very least you shouldn't use it in that way in the presence of an actual mute person. But in today's world the context for anything that goes online is potentially global, and yet strangely we don't see any campaign to blacklist the d-word. I myself have a certain genetic characteristic that pretty much everyone considers fair game for mockery, so I see first hand the inconsistency about how some genetic characteristics are completely untouchable while others are subject to mockery.
In any case, it seems like there is a very strong prevailing sentiment against the r-word, and I don't necessarily have a problem with that. But I grew up in a generation that used the r-word a lot growing up. It wasn't really considered "wrong" at the time, or at least not as wrong. So we used it all the time as a substitute for "idiot" or "stupid." Even though I'm on board and fine with saying we shouldn't use the r-word now, it's so deeply ingrained that it occasionally slips out unintentionally. And whenever you see people in the news or whatever getting in trouble for saying the r-word, it's always people in my age group. I feel sorry for them because people who didn't grow up in the exact same time and environment as we did don't understand just how difficult it is for us to completely flawlessly avoid using that word 100% of the time. So yeah, I think people should have a little more mercy and understanding that people who are very used to a certain word may have trouble perfectly giving it up without making any mistakes. But in this case it sounds like he was given chance to apologize and refused, so I don't have too much complaint in this scenario. He should have apologized.