No, the producers are making a decision, based on consumer feedback. They are not banned from re-airing the episode,they are choosing not too. If you want to watch the show, send the producers an email and offer to buy a dvd, nothing prohibiting them from selling it to you.
Not consumer feedback, just a shrill Catholic group.
If the consumers of South Park cared, it would not be on the air at all. I suppose you didn't see the hilarious episode with the pedophile priests on South Park a few years back.
Nobody censors speech they agree with.