Sure, the stock is pretty funny just hanging out there.

But I do see the appeal of a simple clamp to hold your standard issue weapon. It means there’s nothing specialized in the gun, if there’s a problem with that particular weapon, just clamp another one in, you have plenty of that particular weapon available. Looking at the photo, it appears they just clamp it to the top rail, that’s actually pretty slick in my opinion.

Simple drop-in solutions are often very effective at a low cost.