Why does he bear any responsibility?
See my tag line.
I am by no means mindlessly pro-cop. Previous posts of mine will show that.
But think about it for a moment. The guy reports an armed man in his driveway who was threatening his wife. He then grabs his own gun (no problem there).
Then he goes to the garage, right next to the driveway! That's damn near where he reported the intruder. I understand he was under great stress at the time, but it was a bad move on his part.
From my perspective if I was alert and awake and ARMED, I’d have only called the police afterwards.