I think a lot of us are armchair quarterbacking this way too optimistically. Armed or not, whenever there is physical conflict you should always make space. I thought he reacted like most people would react. (Not saying us, just the general population) Without creating that distance, honestly I dont think that there was anything the victim could do at all.
Honestly, I am not sure if any of you have been in a fight, but I have been in many. I know that sounds bad, but between working as a bouncer for years, security, armed security and even my years in college, I would say that I am familiar with the subject. In control tactics courses we were always taught to make space between you and your aggressor first and foremost. I can say from experience that fights can start up out of no where. I have been randomly and I mean completely out of the blue randomly been sucker punched. I have been laughing or joking with my assailant before being struck, in fact I have been shaking my assailants hand, who was someone I was acquaintances with, pull a beer bottle out of his back pocket, break it over my head, slice across my face on swing two, and come at me to stab me in the stomach where I had gained enough consciousness to shove him back before he stopped. I was 6'0" and 185 lbs and in great shape and he was maybe 5'5" and 110 lbs. I have been rocked several times as well as seen dozens of people knocked unconscious. Things happen in the blink of an eye faster than you can bring your hands up to block it much less draw. When people are knocked silly like that, I can promise you they have literally no idea whats going on. I have had a kid who was knocked out while I was in uniform, gun, badge, A.S.P., OC, vest, I helped him up and asked if he was ok while police were right next to the entire ordeal and that kid swung on me while the officer and I were holding him up. As soon as you are hit like that, your motor function skills barely work and your brain isnt at normal operation either. You are almost 100% defenseless. That is why they teach in school and the academy, an officer can never ever lose a fight again. I will never be the victim again. If you ever get into a situation like that guy did, you are completely at the mercy of those around you period. If you don't believe me, put a dummy gun in your holster, have your buddy knock you unconscious and have a timer and see if after you get knocked out you can even remember to draw in 10 seconds.
I am not trying to say anyone is wrong here with their tactics. I am just trying to provide some clarity to the situation. Once it hits that point, there is zero discussion to be had in regards to the victim, there is probably nothing they can do, and that's without any additional blows being landed.
With that in mind, as a bystander, I am 100% positive I would intervene. I would draw at a distance and shout at him as loud as I could that if he did not stop his attack I would shoot him. If he continued or came at me, I would shoot him. I do not at all want to shoot him and rather he run but in my mind if he is being fatally threatened by me and continues to act aggressively, then the attacker believes that he has matched my level of threat and I would feel justification. I would gladly deal with the legal and financial repercussions because I feel obligated to protect that persons life. Please advise, this is my honest answer and is not my advise morally or legally.