I understand the liability statement of concern, website owners, myself includes place caveats on membership.
i know there is not a true legal issue, as much as possible concerns of liability, I have had to take the same steps on a couple websites I manage for a scout troop, i had to separate the parent message board from the boy's chatter.
I work in the school system as an IT geek, "schools" are required by law (CIPA) to protect students from certain types of activities online. in terms of "online" protection that the "Schools" responsibility, not the content provider.