This shooter may have believed that his possession and display of his gun was going to act as a magic talisman to keep him safe. However, his magic was not effective against a drunk.
One additional factor in the risky behavior (moving closer to an armed man who is warning you away) of the people who were drinking at the party beyond intoxication, may have been peer pressure. The people who were shot probably did not assess the risk properly because they were impaired and also did not want to appear cowardly in front of their friends.
I think that the prosecution can argue that a reasonable person who was actually in fear of their life would have taken the opportunity to leave the confrontation; rather than stand there arguing and continuing to record a video.
A series of bad choices resulting in bad results.
NRA Life Member - Orange Gunsite Member - NRA Certified Pistol Instructor
"When plunder becomes a way of life for a group of men living together in society,
they create for themselves in the course of time a legal system that authorizes it and a moral code that justifies it." Frederic Bastiat