Not sure what the other thread is, but I agree with your option of safety for family and yourself first.
While I will say, drawing a bead and squeezing a round off into a perp pointing a gun is not outside of my abilities or would bother me at all, it is just unlikely as my goal will to be to SAFELY observe and be a good witness.
That said, safely means I might even be out into the parking lot taking mental notes of license plates and reporting direction of travel kind of thing.
I protect my family, no one else. If a serious attack on an unknown person to me erupts right before my eyes, I am going to observe carefully.
My interaction and interference in a situation I am or my family is not directly involved in is going to be proportional to my abilities to get out of the situation completely.
If I am in line at the store and the guy in front of me whips out a pistol and demands monies, if I can not get away from him and he threatens me I am going to be forever impacted by what shall happen and I hope it never comes to pass.
While many do not share the idea, this is why I do not carry extra mags of ammo myself, I really do not expect my pistol to do more than get me to safety or open the path to it.