I'm pretty conservative when it comes to using a gun. I always say the line needs to be clear and hard set. If someone one person is coming at you with a skateboard, it's questionable, maybe you can run or duck. If 5 people are actively perusing you, even with no weapons, you are well within your right to use lethal force. Also, no forearm guy clearly had a Glock in his hand that is no longer functional.
It is astonishing to me that people are attacking a guy with an AR who has just shown he is proficient with it. It just shows the mentality of the mob. Boogaloo may indeed be near.