Stand Your Ground requires clear evidence of malice and in the absence of eyewitness testimony to the contrary. Well, of course there aren't going to be any eyewitnesses or clear evidence of malice. The shooters seem to be (mostly) male and choosing targets rather than defending themselves in surprise situations.
Mr. Zimmerman chose to ignore the very sensible advice of the 9-1-1 operator to stand down (maybe that's how the instructions should have been worded). Rather than wait for the actual 'law' officers to show up and take care of the situation, thereby proving that there was no situation, Zimmerman couldn't bear to let a perp walk.
In his heart, in the heat of his, and only his moment, he saw himself as a hero, and his heroic potential slipping away and it tore him up, and he refused to let it happen. He saw an 'action' moment jump out and try to get away from him, and, like he's playing a video game, with no more thought of consequences than if he's holding a toy rather than a Glock, like road rage in a holster, carried in his codpiece in place of his dick.
Mr. Z. is a type I know well, a frustrated power-tripping wanna-be cop displaying everything that's wrong with unchecked power over other human beings (Google Skinner), and this Florida law has given him everything he's wanted; said unchecked power, the ability and wherewithal to carry a gun and the authority to use it, and absolutely no fear of repercussions or consequences. Wonder if Zimmerman, who's now in hiding, will be charged with anything, and if so, given "community service".
Run, Floridians, if he does. Fella seems to have some hoodie issues.