I think he jumped on because he wants to be a bigger player in the con scene, based on how he likes to present himself and his past roles as far larger than they actually are. He probably figured that he could get in good with Monica, Jamie, and the others and get them to attend cons he's associated with, or more likely (and pathetically) just have some people who might act like he's the hot shit that he wants everyone to believe that he is.
There's probably some of what you say in there as well, but he wasn't on anyone's radar so there had to be some other reason for him to insert himself into this. He's a little bit like the Twitter lawyers seeking validation to fill the gaping holes in his miserable existence.