A man who has been acting violent and now is standing directly in front of you.
That angry/violent man takes a classic attack posture and raises a deadly weapon/knife in a classic attack posture well within range to kill you, no matter if you put fatal rounds into him or not.
He might be instantly incapacitated, he might not. One does not know until you drop the hammer and start putting rounds into the target (like the officer did).
That officer could just as easily been stabbed a whole bunch of times.
Everybody wants to bad mouth the police officer, but if they had a knife wielding madman directly in front of them, I doubt any one of the above critics would be so quick to do anything but shoot to save their own skin.
