I am not a fan of South Park. Nor do I purposely like sticking a middle finger up at Muslims or anyone else for no purpose. The writers of the show probably could have been more subtle and creative and got their point across.
That being said the first amendment covers speech that is sophomoric. The only speech that is not covered is criminal acts and treason. In the work place speech is also curtailed by many other factors. Unfortunately, these rules are frequently ignored or used to persecute people for office political reasons.
The creators of the show had a right to say their piece. Muslims had a right to oppose the episode by the same free speech protections. However, those who threatened physical violence should be arrested. Unfortunately, we have to endure odious speech as part of the deal. It would be nice to tar and feather Truthers, Holocaust Denniers, KKK types and commies, but doing so would make us too much like Hugo Chavez.
The truth is many Muslims are more upset over the reaction and free publicity the counter reactions had. Thia plays into odious stereotypes and in truth most Muslims who live here want to work and are too busy to worry about stupid cartoons.