Depends on when you assume the bad guy is no longer a threat. Clearly, our hero decided the guy was a threat as long as he was alive. I would probably feel the same if someone threatened my wife.
Last thing we need is the bad guys knowing all they have to do is run away to attack another day. Hunt 'em down and eliminate the problem is the only way to be sure the guy 'stops threatening'.
I think assume is the key word here.
If someone threatens my family, I will hunt them down and kill them. I might wait for the police to do their job, I might not.
Then he should have shot to kill instead of firing two warning shots, then chasing the guy down with his car.
This guy was in the wrong.