If you believe he was on the phone with the GF, then you might as well go with what she says, which was TM spoke to GZ first, it wasn't really out of the blue.
Yeah, it wouldn't at all surprise me if that was indeed the case. I can easily see TM getting fed up with the person following him and saying "why are you following me?"
Again, not the best thing to do, but not an unreasonable reaction.
I agree that it's going to be hard to show who actually started the physical confrontation and exactly what went happened since the only other witness is dead. So we are going on a lot of speculation. I just think that given what we know about Z's state of mind at the time, I find it really unlikely that TM is the one who gets the blame for starting the physical confrontation. You got one kid walking home from the store, talking to his GF and a guy who is following someone who is, in his mind, a suspicious person and has expressed a complaint that those "******** always get away". I certainly find the idea of TM attacking Z from behind (as has been mentioned before, I forget if it was Z himself or his father who brought that up) implausible - if the GF is telling the truth, then the whole fight started right when the phone went dead.
If I had to bet, I'd bet that TM realized Z was still following him, then he and Z had a verbal confrontation. Z, tired of those "******** always getting away", attempted to restrain TM until the cops showed up, TM fought back, Z started losing the fight and, in fear for his safety, shot TM.
I don't think Z entered the situation intending to shoot TM, just that he was probably over confident and the situation got out of his control. In my mind, that's manslaughter not 2nd degree murder.
I'm not on an actual jury, so I'm not saying Z is certainly guilty. Just that, in my view, he is most likely to be the one to blame. I think the state has reasonable grounds to bring charges against him, and Z should not be able to avoid trial based on SYG, and if he can avoid trial based on SYG, there's either something we're not being told or the SYG law is completely messed up.