I understand that -- I guess it strikes me that the victim in this scenario (if indeed he's the victim, as it seems there's some gaps in the account?) could have quickly lost his victim status by following his would-be gunman out into the parking lot when he clearly did not need to. Maybe he wanted to snap a photo of him, maybe he was packing too and wanted to make a point, or maybe he would have just got himself shot.
Legally I'm not sure how that would go -- man gets gun shoved in face (innocent victim in immediate jeopardy) -- threat removes itself (no more jeopardy) -- man follows the threat into a parking lot and ends up back in jeopardy (now he's contributed to the escalation of the problem) -- let's say man now shoots the threat in self defense, that would never have been needed had he called the cops and stayed put in Sam's Club next to the 25 gallon drum of peanut butter.
Seems like both sides were doing dumb stuff. But I make no claims to intelligence of my own!
