Clooney was one of the first fans of SP. He showed the "Jesus vs. Santa Claus" short to his Hollywood pals long before South Park started. And he was the voice of Stan's gay dog in one of the episodes, and he did a brief spot in the South Park movie.
I can agree that Clooney got off relatively easily, I think Damon got hit pretty hard I mean basically they said he was retarded and the only words he knew were his own name. Penn got hit the hardest, though the funniest part about that was Penn's reaction, that open letter he wrote to them was nearly identical to the monologue they gave his puppet, he might as well have just announced that indeed he is just as big an idiot as they portrayed.