As I read it, he "ticked" the wrong person off (deal gone wrong ???), and the DHS, BATF, or WTF took advantage of the current climate to shut him down. I know that the Feds will keep you under surveillance for yrs, if need be, and will wait for "just the right moment" to spring when you are weakest. I had a friend years ago, who was involved in a "gun deal", just one that was questionable. They tapped his phone for over a year, and waited until his father died, and served the warrant at the funeral.
I don't know Bob, but I did know Ralph, and it sounds like they were similar operators. We'll never know the truth here, sounds like he was trying to save rare collectables from having to be import stamped and controlled by an over-reaching government, as the main charge.