The great thing about south park is that they have social commentary under the story. This one is titled "the F word", so it's also about the word ***. They make a good point that it doesn't really mean "gay" to a lot of people anymore, it's just an insult. Kinda like calling someone a fucker is an insult, but going by the literal meaning it's saying "you're having sex" which seems like a compliment.
So southpark is saying that *** should be recognized as a generic non-gay-bashing insult. Right on.