http://www.thesuperficial.com/2006/03/13/isaac_chef_hayes_quits_south_p_1.html
The above links to a very "right on", as Isaac would say, article on Mr. Hayes exit from South Park.
In brief, it says the man has been part of lampooning every religion on the planet, but when it came to lampooning his it was a "civil rights" attack, BWAHAHAHAHAHAHAHAHA!!!
Some people think that Hayes, suffering from the aftermath of a stroke, had "representatives" speak for him against his will.