This is self defense. Having been blindsided and knocked to the ground the incident went physical and did not have a clear ending to hostilities. Also without audio, I question if anything else was said when the guy on the ground was drawing his weapon and firing.
https://abcnews.go.com/US/gunman-parking-space-shooting-charged-stand-ground-law/story?id=56715356 I have seen a couple videos... this one is a close up.
Damn so the dude who initiated the confrontation shot and killed the other one bc he pushed him down. What the actual fuck.