Considering reactions to cartooning of Muhammad, I'm not sure that threat was so empty. Still, it's sad the episode was censored.

True, the threat is more credible, but ... free speech, anyone? It's easy to defend free speech when it's the virgin Mary in a jar of piss, while the Catholics complain (but don't go and slaughter the artist). If the 1st amendment is only going to be protected when something is offensive to a peaceful group (or one without the credible likelihood of violent radicals going ape), then you end up catering to the sensibilities of those most likely to be prone to violence.

Strange thing is, they had other episodes with Muhammad with no comment from anyone that I'm aware of.