If I pull a gun and the attacker runs away, I'm not going to shoot him in the back.
I understand why you wouldn't. And, I wouldn't if it is illegal. But, society would be better off if it were legal. You would be saving the next victim.
Thugs don't turn their life around just because they have a gun pulled on them during an attack.
And pretending that guns are good to solve problems peacefully is illogical and counter productive. For one thing, it just passes the problem off to the next poor sole that happens to be victimized by the thug. For another thing, the fact that guns are great tools of violence is the only reason why this was resolved "peacefully" anyway.
If guns solve problems peacefully then maybe we should prosecute people for using them instead of just pointing them.
If guns solve problems peacefully then maybe we shouldn't allow people to carry standard capacity magazines.
If guns solve problems peacefully then maybe we shouldn't allow people to carry loaded guns.
See where I'm going?
The concept of peace is rediculous, subjective, and overrated. Justice is when the victim of an attack ends legally ends the life of the attacker. That is much more important than peace. Actually, it contributes much more to a peaceful society than "peacefully" using a gun to catch a thug, slap him on the wrist, then turn him loose on the next poor victim.