I'm going to have to agree with South Park co-creators Matt Stone and Trey Parker and call Issac Hayes a hypocrite for quitting South Park. (Thanks Karla for the story tip.)
According to the AP story, Hayes, who lends his sultry voice to Chef, said:
"There is a place in this world for satire, but there is a time when satire ends and intolerance and bigotry towards religious beliefs of others begins... Religious beliefs are sacred to people, and at all times should be respected and honored... As a civil rights activist of the past 40 years, I cannot support a show that disrespects those beliefs and practices."
To that, Matt Stone told the AP:
"This is 100 percent having to do with his faith of Scientology... He has no problem — and he's cashed plenty of checks — with our show making fun of Christians... [We] never heard a peep out of Isaac in any way until we did Scientology. He wants a different standard for religions other than his own, and to me, that is where intolerance and bigotry begin."
If I recall correctly, I read an interview with Stone and Parker in GQ a couple months ago and the interviewer asked the pair why it took them so long to do a show about Scientology. Parker replied:
"To be honest, what kept us from doing it before was Isaac Hayes [who does the voice of Chef]. We knew he was a Scientologist. And he’s an awesome guy. We’re like, Let’s just avoid that for now... Finally, we just had to tell Isaac, 'Dude, we totally love working with you, and this is nothing personal, it’s just we’re South Park, and if we don’t do this, we’re belittling everything else we’ve ripped on.' "
Stone and Parker took shots at Jews, Muslims, Christians, Mormons, etc., multiple times over the course of South Park's nine years and, out of courtesy for Hayes, left Scientology out of their line of fire. I agree that the time had come (especially with the surplus of Tom Cruise material available) to finally level the playing field and take a long-overdue shot at Scientologists. The episode aired last November.
I'll keep my analysis concise: If you dish it out, you better be able to take it. Don't laugh at others if you can't laugh at yourself, Issac. You are a bad mother -- Shut your mouth.