Keep RP off Party Finder. It does not belong there. There are plenty of places people can do RP but you should reserve your better judgement and leave it to people that actually use it for its intended purpose.

As for the moral implications of doing "ERP" in a MMO with people of all ages: It's fine, but if you so happen to do it with a minor be prepared to deal with the full consequences and rightfully so. As an adult you are equally responsible to the parents in how your behaviour affects society as a whole. We do not live in a jungle, therefore everyone has an equal share of duties they have to commit to. If you so choose to be funny and acknowledge this risk all the blame will be placed upon you and neither I or anyone else for that matter is going to sympathize with you.