I have a Nazi dagger. It’s a war trophy brought back by a relative who was in the victorious American Army. Victors often bring back war trophies of this nature, and said trophies get passed down. I am damn sure not a Nazi, or a Communist, or believer in any other totalitarian ideology. Though those issuing death threats to this antique shop owner may well be.
Come to think of it, I built an Me-109E model when I was a kid. It had swastika decals. Oh noes!
If I were going to sell such a flag, I would not unfurl it and hang it on a wall. I would fold it up and put it in a display case. I would not want to be confused with anyone who would display that flag proudly. As a war prize, it is priceless. As a display flag, it could be easily offensive.
I could have written the same thing.
I also have a stamp collection with swastikas on many of the stamps. The collection was amassed by my great-grandfather who died before they could kill him. His wife and one of his daughter's families wasn't quite so fortunate.
ML/NJ