Tough to say what the right response should be, but one might be not to answer the door if you don’t know who is on the other side. If they start breaking down the door without identifying themselves (even then you don’t know for sure)it is decision time.
Yes but in the middle of the night he may have not been thinking as clear as he may normally did when he was fully awake and alert.
I would not have opened the door, would have had my gun and been confirming they were actual cops.