Come now, we saw Eric Cartman naked long before Bart, so no big shock there.  But it was pretty funny when it did happen as they were doing all sorts of unique things to cover it, and then WHAM.  Hahahaha, the audience was roaring with laughter.

On a more serious note: Child Nudity does not equal Child Porn, otherwise all those parents who snapped pics of their babies naked in the bath or something, would be in such serious trouble.   Child porn is sexualization of children.

As for Renderosity and fairies, I agree with their stance.  I see it as a more cautious than sorry stance as someone might push it too far to the limit and we'd all be guilty by implication.