If you believe that Palestinian "incitement" is a powerful impediment to peace in the Middle East, then you think words matter in that context and you ought to acknowledge that they probably matter back here too. If you're worried about the dangers of nationalist rhetoric in the Chinese media, then you recognize that what elites and major media figures say can affect what masses perceive and what some individuals do. If you are one of those people who think that what madrasas in Pakistan teach is a source of terrorist violence, then you understand that violence sometimes arises because of what other people have written or said (sometimes over and over and over). If you believe that Mein Kampf had something to do with convincing Germans to commit genocide, then you've acknowledged that words do matter and sometimes they pave the way to unspeakable acts. So why deny it in this most recent case?
And here's the central point to remember: Violent language and hateful political rhetoric don't make most of the people who hear it run out and kill. Rather, the problem is that it makes it more likely that a handful of more fervent, less stable, more susceptible, less socially connected individuals will hear the message and take it to heart. And in a world where guns are cheap and plentiful, all it takes is one.
The solution, needless to say, is not censorship. The solution is to view those who favor violence as a way of dealing with one's political opponents with contempt, and to treat entertainers who use such language and tropes as moneymaking devices as beneath even that. I don't want the government telling Glenn Beck, Bill O'Reilly, Rush Limbaugh, or any other xenophobic whack job what not to say; I just want sensible Americans to switch the channel and confine them to the obscurity that they deserve.