"Self-defense" does not extend to others by definition (hint: the term "self" says it all). Really, this is not rocket science. If you think this shooting was morally acceptable, that is your privilege. But it was not self-defense in any reasonable shape or form.Self-defense extends to others. If someone is threatened with lethal force, a third party may use lethal force to protect that person. And this robber was threatening everyone in the restaurant.He should have waited to see what he would do. If he turned, shoot.
Except you can legally defend others (although some states limit who you can defend.) At the time the guy shot the robber's "gun" was pointed pretty close to a customer that's off screen. (Watch the start and remember where people are.) If you choose to defend a third party you step into their shoes legally--you have only the rights they have, if they have somehow unknown to you forfeited the right of self defense then your actions become unlawful.
Moving towards doesn't mean it's over. The guy chose to pull an armed robbery in a place where there's a decent chance someone is packing--he's a grade A moron. Sometimes morons do stupid things like shoot the victim because they didn't get as much money as they were expecting and decide the victim was holding back.We do not have any audio, but the video clearly indicates the robber was moving towards the exit. Which suggests to those who are neither visibly nor reason impaired that the robber was not a threat.