The fact that this idiot left the scene instead of immediately reporting what happened, tells me he knew he'd done wrong. What he should have done was called 911 - from the scene, preferably before shots were fired - and kept them on the line until police arrived.
I don't know how the law is worded in Florida, but here in VA, you only get to 'stand your ground' if you did not contribute to the problem. Going up to a car full of kids because they are playing music (or something they believe to be music) louder than your liking is contributing to the problem. If he truly believed he was in immediate danger of death or grievous harm, then he might have a case, HAD HE NOT PROVOKED THEM BY STARTING THE ARGUMENT.
As it is, I think he's (justifiably) screwed.
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