Where did the deputy get the idea that he was entitled to search the house?
From hell.
It used to be that we knew the schools were full of libs. But the cops were (generally) on "our side".
I'm not so sure any more.
I used to live in Calvert County. The deputies there had a reputation for being heavy-handed. They would stop cars driven by teenagers, without apparent cause, harass them, and search their cars without warrants.
By the way, the sheriff (it’s an elective office in MD) when I lived there was a conservative Republican, and I campaigned for him. The conduct of his deputies was puzzling and disturbing to us. Calvert County itself, unlike more urbanized parts of Maryland, is conservative and full of gun-owners. I was a precinct captain there and never had any trouble getting campaign volunteers. They were a great bunch.