This was posted elsewhere here, where I commented we may need more info. There is a video showing him shoving a girl to the ground prior to being chased. As we recall, we discussed here the Florida incident where the guy was forcefully shoved to the ground and we all felt him shooting the shover was self-defense, even though the shooter was a loudmouth who may have instigated the events.
In this case, if the video is accurate, the shooter started the situation by shoving the girl to the ground, so there may be some blame for him. That said, the part of the video that is making the rounds clearly shows multiple aggressors chasing him, hitting him with skateboards (deadly weapons), and yelling "I'll f'ing kill you!"
Those three things together create a situation where to me, he can defend himself, as I would genuinely be in fear of my life at that point. However, his physically attacking a girl beforehand needs to be part of the discussion. And again, more info may come out.
Regardless, it appears he has had some defensive firearms training.