Trey Parker or Matt Stone did an interview over Comedy Central caving in to the pressure and censoring Muhammad.

Trey Parker: So Matt and I were like, “This is great; we have our first episode.” Comedy Central kept saying, “We’re not going to broadcast a Muhammad episode.” And we said, “You totally have the right, it’s your network, but we’re going to make one, and it’s going to be one of the seven you pay for.”

Matt Stone: And then we made it two episodes out of seven. It was life imitating art, because the whole week after the first one aired there was a teaser “Will television executives take a stand for free speech? Or will Comedy Central puss out?” That whole week we were trying to get Comedy Central to show Muhammad. And they pussed out. They did show most of the episode, but they blocked out the specific moment when Muhammad appears. I know people who assumed you decided to run those title cards yourself, as part of the satire: “In this shot, Muhammad hands a football helmet to Family Guy. Comedy Central has refused to broadcast an image of Muhammad on their network.”

Here is the Family Guy part, not censored.

Muhammad and His Salmon Helmet – The top video clips of the week are here