Good point, DNS.
I'll also state that a mediocre shot, who is hell bent on killing, is going to be a lot more effective than a IPSC champ who can't bring himself to fire on a human being- or hesitates too long if he does make the decision.
This is precisely the reason we train cops to make the force decision based solely on the other party's actions. You do A, I do B. It minimizes hesitation, thinking too long or anguishing about what must be done. You picked it- not me. I just happened to be standing in your way on the day you sealed your fate.