I understand your concerns and point, but personally I believe it should be checked, their public post not private post. I see crazy post on the Internet daily and I keep wondering if those set of humans stay around kids, funny enough they could be teachers too . Many kids look up to their teachers and see them as role models, just imagine the teacher publicly post things that are inappropriate...

It's fair to check public post, you don't need their password to do that. Kids really need to be protected in and outside the school environment.