It it was unclear that the man had broken any laws, why did they confiscate his property?
Why was it important, in the context of the story, that the man was Amish. Is that better or worse than being Baptist?
There are a lot of people who collect a lot of different things. I once saw a (new) condom collection in an "antique store."
The government issues a license for "firearm collectors" to collect certain types of guns. For one thing, it allows a collector to buy certain types of collectible guns through the mail without involvement of a licensed firearm dealer. The license does not limit the size of the collection, nor does it forbid selling of some of the collection.
Someone with a collection that size is unlikely to be gathering in weapons for a revolution. He has too damn much money to lose.
There are a lot of good people, including dyed-in-the-wool liberals, who collect historic firearms. It does not make them revolutionaries
or criminals. Don't get me wrong, I have no idea if the man was breaking any laws, and apparently the police didn't either. What is certain, is that he will have to spend money to get his property back...
My brother is a Yellow Dog Democrat, as liberal as they come, and he collects fine WWII historic weapons. He is neither a criminal nor nor planning to bring down the government. Historic firearms are a great investment. The value of the firearms has nearly quadrupled in the last 15 years. There is not much difference in investing in Raytheon and buying a Garand rifle, or is there?
The people that you need to worry about are the ones who have a dozen AR-15s and march in the streets shouting Sieg Heil.