I am no fan of the show, and I'm not likely to ever be one. But I am of two minds on Murphy's comments. On the one hand, he seems waaaaay over the top regarding "The Kings of Leon". If an artist does not want their music used, well.. I can easily understand that. Murphy's reaction isn't going to help him one bit, and it's liable to have an effect on other artist's interest in letting their work be used - just as others have said already in here.
But now in regards to what Murphy said about Slash's comments... well, put yourself in Murphy's place. Sure Murphy was needlessly caustic, but Slash really came down hard on what Murphy has poured his heart and soul into. Someone trashing it the way Slash seems to ... well, it's understandable to respond angrily like that isn't it?