You're justifying shit writing, fanboy.
He vowed to protect her so he should be doing it by whatever means necessary. Say you have a gun in your pocket but you hate the idea of shooting someone, but the closest person to you is about to be kidnapped. Are you really not going to shoot on principle? So what if the situation is going to escalate, how does he know if he has another chance?
He got the shit kicked out of him because he never TRIED. And unless you know more than others, I assume he doesn't have fucking background reports on the punks he fights so he never knows who's going to be a "deadly serious enemy."