I wasn't aware of that, it was never censored on my PBS.

Yeah, I can see why they would want to avoid any offensiveness (I know about gas chambers, my Grade 8 Reading teacher was OBSESSED with the Holocaust), but I serious doubt little kids are even going to get it, they probably just think D.W. is saying exactly what's on the tin: being trapped in a small, closed area, with Kate's soiled and smelly diaper.