Everyone is making some really good points.
Right now, outside of school, he doesn't really have any "friends". In the 4 years I've known he and his mom, they are on their 3rd apartment, so that tracks. He has a could of step-brothers on his dad's side that he sees every other week when the kid stays with him, but they are a bit older so i'm not seeing them get into it. His mom just got approved for a home loan so hopefully they will settle down in a more permanent place where he can make some friends in the neighborhood.
All I really want to do is get him into SOMETHING, and, for all the reasons stated upthread, 5E is a good starting point because if he ever gets tired of hanging out with a bunch of grown-ups, then he'll be able to more easily assimilate into another group where, if they introduce him to a new game system, he'll at least be able to transition more easily.
But, for the time being, it's just gonna be us once a month or so.
Thanks all....