If I'm not mistaken I think it varies from PBS station to PBS station. So it's really 50/50. If I were directing/producing this I would pull the camera back for a wider shot of the stage. That way you're not focusing on the bare bottoms but you still get them and the reactions.
It's one thing to bleep a word but to only show the reactions to something that the audience at home can't see just defeats the purpose of the whole scene.
"All our dreams can come true -- if we have the courage to pursue them." -- Walt Disney
We must have different Gods. My God said "do to others what you would have them do to you". Your God seems to have said "My Way or the Highway".