Did he call 911? Did he think to get an ambulance?
No.
He turned his back to her, went and found a different weapon, then came back and leisurely finished her off at close quarters.
Then he packaged her up and made himself some dinner.
This thing isn't even human.
That puts an entirely different light on it.
Unarmed is irrelevant if they broke into his house - so leave that emotional rhetoric out of it - but finishing off the wounded girl, who was no threat at that point, was waaaaay over the top.