Should politicians and political appointees?

have the right to censor entertainers? This question was inspired by the Missouri State Fair officials banning a rodeo clown from performing ever again at the fair because they found his wearing an Obama mask and asking if the crowd wanted to see him trampled. I seem to remember comedians taking shots at George W's intellect, Bill Clinton's amorous activities, Nixon's honesty, Reagan's equanimity, Ford's balance, etc. There was no outcry then, so why now? What's so offensive about asking if a representation of the president who many feel has trampled their rights should be symbolically trampled?