I have hidden the worst thread I saw (I'm on vacation still but felt it was pretty bad) as well as a couple of the stupid comments.
I also think leaving a comment as Wikipedia warning the user who made the thread I hid would be good. I got a 2nd opinion from Philippe (no one else was responding) but am going to wait for 20 minutes before I post. Will go ahead and do so if I don't hear anything to the contrary. What I plan to post is below (this is in response to their latest post in the thread about how you have to respect other peoples opinion, I don't have to accept your opinion that someone is a 'disgusting beast' on our page, no) :
You are welcome to have your opinions Kitty, however you are not welcome to say something like that here. This thread has been hidden (it is still visible to you and your friends), I am happy to delete it if you'd prefer. Further comments along these lines however will cause you to be banned from further discussion on Wikipedia posts.
I'm not against having a more formal safe spaces policy that we post on the facebook page (we can't moderate Twitter much, we can google+ though I think? at least on our board). I would prefer we have a light hand, but these comments were not borderline.