From information on his site, he is a one man machine shop. He makes a couple of other things, like a folding target scope stand, and this business is a second job for him. He has a full time job as a design engineer.
I have no idea of the volume a one man machine shop can turn out, but it doesn't sound like a good way to get rich quick.
It sounds more like a guy who came up with the thing because he wanted one, and then sells a few on the side to help support his shooting habit.
I think you're right.
My gunsmith is the same way. He is a machinist by trade, makes his "bread money" off his day job, makes the "good" money off custom machining, and is just a gunsmith on the side (turned a hobby into a slightly profitable venture). He sells a few "machinist's" tools (primarily assembly jigs, from what I understand) for extra cash, but he never created them with the intent to make money. He made them for himself
first, and decided to make the product available to others some time later.