Here's the video so we can avoid what did and didn't happen.
A capital idea.
As you can see, the three men drove up to him, threatened him, told him they'd go grab a gun too, then assaulted him
I didn't see an assault. There's a cut at 2:44 he tells the dispatch that he is going to tell them stay back that he wasn't 'losing to these people anymore' then there is laughter the camera points downwards and there is what sounds like it might be a gunshot.
It's certainly consistent with him being assaulted, but I don't see it as certain. They could just be mocking him or winding him up (a stupid thing to do, granted). I'd like to know how long the gap was in the cut, I could certainly believe if one of the men left the scene long enough to have in theory brought a gun back as he threatened, that he might reasonably be in fear for his life.
That said, the Stand your Ground law seems to have claimed another victim whose crime seems only to have been an asshole when he's drunk. A much better solution I think would have been for the shooter to return home and stand his ground there. That way, if they're just drunken assholes mouthing off nobody gets hurt in a moment of fear. If they really did intend him harm, they'd have to break in to his house and he'd have a more defensible position (both physically and legally).