My example was an illustration of the general legal principle. My end point was that if he was not justified in pulling his gun, then claiming SD in relation to the gentleman rushing him becomes a hard sale. He escalated a push and allegedly some threats to a gun fight. The alleged threats, notably "I'll kill you" weigh in Ung's favor.
Mr. X chose to take it past words and into violent actions. Why is that so hard for you to accept?
That alone is not enough to justify using a gun. Typically the standard is not did someone do violence to you, nor is it even are you in fear of imminent future "violent actions". It is reasonable fear, in the circumstances, of imminent death or serious bodily harm (which has a particular meaning). In most cases someone pushing someone else would not cause an objectively reasonable fear of death or serious bodily harm. Particularly when another person has already come between you and the pusher.
Almost any time an armed person shoots unarmed person there are going to be serious questions as to whether the purported fear of death or serious bodily harm was objectively reasonable. That is often a difficult determination this case is just one example of that.
I'll repeat my point so that it is not misunderstood.
Based on the video alone, Ung's actions look very questionable. Depending on other circumstances things may alter that analysis. I do not have an ability to know those other circumstances or even make great judgments about them. One of the reasons appeals courts don't typical review findings of fact is because it is recognized that those in the courtroom hearing the testimony, seeing the people, etc, are in a better position to evaluate credibility etc than one reading a transcript.
As I have stated multiple times, if the guy was making threats to kill, etc that might make it all look more objectively reasonable.
What is objectively reasonable is by nature a debatable matter. A point worth remembering.
The take away from this case, and a number of cases that are roughly similar to it, is that a bunch of other people are going to be reviewing your actions and asking if they are reasonable in the circumstances. The more clear the threat is and the less culpable you are in that threat existing the better it is for you.