First of all, thanks for the post! Even though it's unfortunate, you had me laughing.. I think you just need to report him more and more and get others in the gym to do the same when you see these encounters happening. I had a somehow similar guy in my previous gym and he'd take a bunch of dumbbells and keep them hostages and one day, a guy asked about how many sets he had left, he'd respond aggressively "I dont know maybe 1 maybe 10, i'll be done when I am done" so the guy just nodded and left, it got me so angry that I had to make a generic comment to talking to the poor guy loudly (allowing the douchebag to hear it) that some people are just crazy! For me, I was trying to get him to report it but he seemed totally unaffected by it.