Not much to go on, but do notice that three .45 acps and the deceased was still able to flee "about a block."
Of course, the three .45 acps did their job by stopping the attack and turning it into flight, but I'd be a little more confident if the robber dropped where he stood.
Also, the defensive shooter was somewhat skilled, so you have to wonder how well a less skilled defender might have done with regard to shot placement, or how many shots it might have taken to achieve the same result.
Food for thought.
Glad the good guy prevailed and saved his mom.