As long as he's in my house he's a threat and I will continue to engage until he is neutralized and no longer a threat, or he's outside of my house and no longer a threat. As long as he's in the house I don't know if he's trying to escape or trying to regroup and come after me again. The victim took the correct action in this case.
The victim left cover. I would remain behind cover in my BR, unless their are innocent third parties in the house. No mention of children, if I recall. If he enters through the doorway -- the kill zone -- he will be shot again.
I suspect he has had enough of the gunfight. The intended victim turned about to me armed. The attacker thought he could have his way without push back. The attacker now has a new "perspective".
The victim took an unnecessary risk.