I am a licensed secondary educator, and though I have been out of the game for a few years now, I used to substitute teach at many schools. There is certainly a "vibe" at each and every school, but I would never say "So-and-so is from _________, therefore he/she is _______." You admitted yourself that it is stereotyping, so why even bring it up? It serves absolutely no purpose other than, like I said, to not-so-subtly jab a certain group of individuals. Since that was your intent, well played. You have shown that you are better than them. Congratulations.
If you knew him personally, and knew anything about his situation at all, then of course bring it up. But since you don't, you're throwing blanket statements on a group, and assuming those traits to be true of a certain individual from that group. Have you ever heard of a "fallacy of division"? Go look it up, educate yourself, and then engage your brain before you click on that "submit reply" button.