Perhaps, killing is easy in past human eras and on different continents presebt era. I disagree somewhat. The weapon in someone's hand depends on the cultural environment from which they are in I somewhat disagree with this also. Most people I know training for Vietnam, or over there, were never hesitant to shoot back. Mainly out of fear of being killed. Also, I disagree with human "instinct" I disagree, The population is not growing because of better military training and weaponry.
I wouldn't begin with the intention of killing him, I would wish to do what's necessary for me to survive the encounter. if this results in him dying then so be it, I wouldn't hesitate for a moment. " Don't fight an idiot - he'll bring you down to his level and beat you with his experience"
The key is knowing where that switch is. Killer instinct is not a sledgehammer is is a scalpel, and like all blades it needs to be sharp
I said yes, but I'm not sure whether or not I could kill. I'd have to come to it. Under the situation you described though, I would be trying to incapacitate. Never kill unless it's absolutely necessary is my philosiphy.
I don't think many would disagree - but you might not get the chance to escalate your response and may have to make an instant decision to kill...that is where it gets dangerous and or tricky if you have not prepared for it