Why are people so fucking prudish?

I was watching Real Time with Bill Maher and I got kinda shocked on how prudish even that show is. It's not the first time but I can't believe no one, even Janene Garofalo, said anything about how ridiculous it is that one wouldn't be able to talk about Anthony Weiner sexting with your kids. And because of that Anthony Weiner should resign. I can't even begin to fathom the logic behind that reasoning. I cant even grasp why you would want to talk about your kids about his sexting and feel that you couldn't. Sharon Waxman even says that she talks about Anthony Weiner with her kids so they are old and mature enough to talk about real world politics but to young to handle any talk about sex? Where does this insane fear towards sex comes from? Why is it set in stone that anything to do with sex should be kept away from children? And why is it Anthony Weiners fault that Sharon Waxman can't talk about sexting with her kids? And why the hell doesn't anyone even bring up how silly it is?
I'm just flabbergasted. This is on HBO hosted by a foul mouthed comedian with one of the most outspoken and active liberal media figures on the panel and yet it is completely accepted without question that you can't talk to kids about sex in any way shape or form.
What the H?