I agree with Peter T that the issue re: George Harrison justifiably raised the ire of many (including me). I think Peter T's comments attacking the statement were appropriate. I think the comments in that thread attacking the person making the statement were not (I don't recall if Peter T's comments were personal).

Sometimes it is difficult not to respond personally, when people make a deliberately provocative statement - but there should be rules about fighting. Attack the comment, attack the behaviour - do not attack the person.
There is a world of difference to the addressee when he/she hears "You are an idiot," as compared to hearing "You are acting like an idiot." Attack the behaviour, not the actor.