But I thought that GZ was "returning to his car", I would consider this as an act of retreating, which if true would be why the defense didn't use SYG as a defense. It would seem that there is not much sense for the judge or jury to place such weight on this aspect of the law. If you're retreating from a place and you're attacked, then you have the right to defend yourself in all 50 states - since you have satisfied the duty to retreat, though in the 37(?) states that do not support SYG you would have to prove that retreat aspect as a part of your Self Defense claim.
I used to think it was terrible that life was unfair. Then I thought what if life were fair and all of the terrible things that happen came because we really deserved them? Now I take comfort in the general unfairness and hostility of the universe.