Your last sentence is very telling.... you may not agree, but you, personally, have provided the platform for the offending poster to say that he wished Morrissey had cancer. When Morrissey says he wants Johnny Rogan dead, or Margaret Thatcher's head lopped off on a guillotine, or a lot of other things that he says, he often takes a lot of stick for it... right up to being investigated by the police for various comments if memory serves. But in any case he accepts the consequences of his free speech without hiding behind other people. Complaining that he was taken out of context by a journalist is very different from complaining that his unedited words aren't his responsibility.
By your comment that you disagree, it sounds as if you want it both ways - you want to have (and by extension your posters to have) free speech, but you refuse to take responsibility for and feel slighted when you have to suffer from the consequences of providing a very public platform where comments wishing harm on Morrissey (or other posters - the only time that kind of thing seems to be taken down is when it applies to a mod) is tolerated, free of consequence.
It would even be different if this site were called "musicchat.com" or something like that, and it were a general forum for discussing anyone and most importantly (since the "other music" forum exists) if it DIDN'T HAVE HIS NAME ALL OVER IT. You are using HIS NAME to direct traffic to this site - essentially using his name to advertise this site as a place for discussion, and therefore he has the right to complain when it becomes a platform for hate directed at him, other posters, and generally projecting a very bad impression - through the comments posted here onto HIS NAME. I'm not even saying that he has a legal right to stop it, because I'd assume if he did this site would be gone by now. But he has an ethical right to stand up for himself in the way that he has, and the atmosphere in the site where deathwish statements such as the above, just as one small example, are tolerated is YOUR responsibility, because you make the rules here.