I've observed his behavior at times and found it to be somewhat amusing, while also getting annoying and rude. As with anyone annoying, if you reply to him and get involved, you're only egging him on. I've seen numerous folks who've felt the need to respond to it when they could simply let it pass and move on. I do believe that if he's being honest about his age that his youth may be a contributing factor. I also feel that he's definitely cooled off in the past few weeks. Perhaps your earlier "discussion" with him has had an impact, and this will also serve to calm him down. IMO: One more chance, then if nothing changes, adios.