"This is an all talk server. Conversation may be of an adult nature and not suitable for children"
This warning is seen at the begining of every map. Trying to enforce an age limit would be impossible. I mean, I could be 9 for all most of you really know

IMHO its up to parents to keep an eye on what their children are up to on the net. Of course, thats easy for me to say having no children.