Can you go more into this, I do not know the deeplore on Sig myself, .org always seemed like people who should have been satirical but were not so I never bothered signing up there. I did lurk sometimes as I enjoy lurking many sites to get the full story on events myself, but I do not know too much about him.
Is he really lonely in DMs? He seems like a raging asshole in public so that would be a nice thing to know it is just an act.
How would you be held legally responsible? Without you having ownership or partial control of the site it is clear that you could not be held liable. It's like a killer accusing someone else of doing it, the cops do not drop what they are doing, they go "Okay person holding a bloody knife, drop the knife or we shoot".