There is no way in hell he snitched. He just got told (and probably already knows, come on, you think he didn't learn this in grade school?) that's the one thing these people hate most. He also just got told Wannabe Concussion Kid's beating was "a test" though I'm less certain this is directly relevant.
What is relevant is that Spencer Reid is a master of misdirection and of manipulating people, especially psychopaths. And I don't think the people he's being beaten up by are even the psychopaths that he's manipulating right now; I suspect he's just using them. They don't seem like the real threat to him (ah: the other thing he was told was that they didn't want to kill Wannabe Concussion Kid). The psychopath who is the real threat -- and also the real puzzle, which means a potential clue -- is the guard who's blackmailing him. (I don't overly trust the other ex-Fed either come to that.) So I think Reid is doing what he does best: playing chess, and he can see the board.
And if that involves
And when he doesn't have a gun in his hands he uses words, and that's when you should be really afraid. Especially if someone he identifies with/feels protective of is being bullied. You don't want to be the bully in that situation, and you really don't want to be the person in a position of power who ought, but can't be bothered, to prevent that bullying.
And if you think I'm overly optimistic about consistent characterisation because yes, Criminal Minds has hella gone downhill since seasons 2-6 -- it's also been climbing somewhat recently. (I swear quality improves when Prentiss is around, and same goes for Tara.) And the writers have been almost going out of their way to remind us, with Rossi's artwork and JJ's mention of liking football, for example, that they do in fact remember those early seasons.
Reid has deliberately set up the situation so that he'd get beaten up. Precisely what he plans to do with the results of that I don't know, but I expect it will be good.