I'm not convinced that he actually left the area around the T. The point is that Zimmerman and Martin both had a legitimate purpose in a common area. Neither had an obligation to leave. The question is set up to elicit a response that Martin should have done this, to which the racial grievance cultists add because he was black.
Martin had no legal or moral obligation to leave the common area because Zimmerman was there. Marin did have a legal and moral obligation to not break Zimmerman's nose, mount him and continue to drive his head into the concrete sidewalk to the point that he one planted in his chest.
It's not a hard question, really.
I agree entirely with your first point as to neither having an obligation to leave the common area, and I think it was well put.
But as to your point about breaking Zimmerman's nose and driving his head into the concrete - I call BS on this.
First and most importantly, the injuries by themselves prove little to nothing - because they are just as consistent with Martin defending himself from Zimmerman who may accosted him on some way, as they are with Martin attacking an innocent unsuspecting Zimmerman. The only corroboration as to whether it was Martin defending himself or Martin attacking Zimmerman is Zimmerman's own statements which are full of gaping holes, contradictions, and some pretty absurd excuses. Nobody claims to have seen the start of the physical confrontation either, so it's not like we have reliable witnesses to draw from.
Also, the physical evidence simply does not support this narrative about being seriously beaten. As to the nose, there was never any definitive diagnosis or confirmation that it was actually broken because Zimmerman never bothered to follow up on the imaging referral. Also, we know from pictures that the swelling subsided very quickly. As to the minor lacerations on the back of his head, they were so insignificant that they literally did not even require a single band-aid. Just a few minutes after the alleged life-or-death fight ended, the EMTs on scene administered a test to check for signs of head injuries and they found nothing that caused any concern; he scored a 15 out of 15 on the Glasgow Coma Scale. They checked his vital signs and they were within normal range. In terms of "treatment", they merely wiped him off with peroxide and sent him on his way. He never sought nor required any additional treatment after that.
Say what you will, but the injuries were utterly insignificant and most certainly were not even in the ballpark of causing serious bodily harm or death. I don't see how anyone can say the physical evidence is consistent with Zimmerman's narrative.
Stack on top of all this that Martin's autopsy revealed a complete lack of any corroborating evidence of this alleged life-or-death struggle, and it becomes near impossible to believe Zimmerman's tall tale.