I also was thinking the same thing. What would I do if this happened in front of me? You can see people and cars passing by just outside the doors. If I was standing directly as the camera is positioned, I would have a hard time discharging with no back drop but pedestrians and cars. I would have tried to slide to the left and engaged if possible so I'd have a wall as back drop. I carry 45JHP and at that distance after going through the BG it would keep going. BUT this is Monday morning quarterbacking not tenths of seconds.
I'm sure someone will disagree with me but there it is! Don't think I really could be at the scene without engagement. I just ain't wired that way.
"The smallest minority on earth is the individual. Those who deny individual rights cannot claim to be defenders of minorities." --author and philosopher Ayn Rand (1905-1982)