I think that it was sensible law enforcement, something that is as extinct as the dodo bird in the cities. The man found a guy under his child’s bed and decided to shoot the criminal, no matter how far he ran away.
That's often said, but it's not always true, is it? Criminals come back, sometimes for revenge. I've seen it in news items, but don't know how common it is. From a safety point of view, when you're talking about home invasion, I'd think the threshold for "no longer a threat" is when the criminal is no longer breathing.
“...If the perp was fleeing the scene he was no longer a threat. There has to be more to this story.”
No longer a threat to whom? The home the criminal just fled and could come back to in order to do further harm or victimize others in the community?
The recidivism rate for criminals within three years after they get out of jail/prison is about 65%.