I agree. This is a home, not a church or business. I wouldn't like it if my neighbors had 50 bikers over every Saturday either.
Seems they are in violation of a city code. Here's an example. You can have a garage sale, you can even have a couple a year, but at least around here you can't do it too often or they make you get a permit. No one wants to live next door to a perpetual yard sale. I thinks its perfectly reasonable.
It worries me that they were told it was a legal problem and ignored the government which violates Romans 13.
To some folks they aren't different but they can go stuff it ~ they are simply in the wrong country and should go find one of the other 134 in this world where things are different.
For me, that would be entirely dependent on whether the proprietor kept a good stock of very-good to excellent condition used firearms in his inventory...
;-)