Well they decided to act as the only ones in media with the stones to do the right thing....maybe? John Noonan at the O Club has what I think is exactly the right take on this.
"South Park used the Family Guy as a metaphor for their own show. Trey Parker and Matt Stone announced to the world that they will caricature Mohammed next week, and dared Comedy Central to stop them."
I love these guys. I would be hard pressed to find better examples of why this country is great, than these two and the holy terror they wreak on hypocrisy, pomposity and intolerance, generally by skewering the so-called forces for tolerance.