I think people are making too big of a deal of the whole "scared" thing. When I was 17 I probably would've done what he did, except for assaulting GZ. Here's what I could see happening. You're initially freaked out because some guy is watching you, asking questions, whatever, so you take off. Once you're out of sight you relax a bit and you want to go back and see if he's still there, see what he's doing, or whatever.
17 year old me (I'm 31 now, I was never in trouble as a teen but I had a normal 17 year old male attitude) would've probably just left after I went back and saw him still there, and if he started questioning me I would've told him it's none of his business. I would've left it at that, but someone that's more aggressive might've gotten pissed off and sucker punched GZ. Just speculating, obviously, but I'm not sure why that's so hard for the TM supporters to believe. Of course that doesn't mean that TM deserved to die, but there's consequences for your actions.