That's what I've been saying since my first post.
Just sue him and make him pay for his sick behaviour.
That is going to be very difficult if they haven't already identified the identity of JackpotRacer with whoever the user is on their platform. Because you can't just walk to the forum administration and ask for IP addresses, and even if you somehow had them, that's not enough information to identify the user's name, address, etc. to say nothing about how are you going to sue someone in a jurisdiction you are very far away from.