As low down as thieves are, no one was in jeopardy of losing their life. I would have stayed out of it. If they did not find any kind of weapon on the dead guy, the shooter will probably be charged.
Not enough information present to make that statement with any certainty. I worked numerous shootings where the "good guy" had a firearm, "bad guy" did not, and the "good guy" either wasn't charged or a Grabd Jury cleared them of all wrongdoing. For instance, worked a domestic where the husband was beating the wife very thoroughly with his bare hands. She got his S&W M-15 out of the bedside drawer and ventilated him thoroughly with it. No charges.
As a LEO of over 20 years, the bad guy doesn't have to have a firearm for it to be a "good shoot". Nothing was said in the report about what the perpetrators' actions were, one way or the other.
For instance, there are multiple perpetrators. If 2-3 "bad guys" were giving you a royal beat down, could a "reasonable person" (that's the legal standard, the "standard of reasonableness") feel that their life was in danger, or they were under threat of serious bodily injury?
For that matter, one "bad guy" overpowers you, has you down and is fixing to do a curb stop on your head. Would you feel that your life is in danger, or you're under threat of serious bodily injury? A reasonable person would feel so, or at least that's what has been held up in court over and over again.
Additionally, you don't have to feel that your life or health is the one being threatened; you can intervene to protect a third party. Article stated the gun toter was helping the Wal-Mary employee. It could be that the employee was being curb stomped, gun toter intervened to save him/her.
I agree it could easily be the other way around; the gun toter was trigger happy and overreacted, but with the little bit of information in the article no one can say for certain one way or the other. That's what detectives/Grand Juries/trials are for; judge or jury is presented ALL the facts and a determination will be made.