I'd have lost that one then. I heard the same thing from a police officer, who was adamant that a homeowner should automatically know it was the police by the way they were dressed, and how well organized and efficient they were when they entered the residence.
It could be that when my father told me this, he was aware of speaking to his daughter... who he wouldn't want to get in harm's way if the police didn't follow their protocol. :)
My point to him was, if I am in my residence and ANYONE barged in, why wouldn't I have the right to raise my weapon in protection? I hate to think that a police officer is above the law. Maybe I'm missing some delicate nuance.