Just to be clear, Crooker was not involved with a paintball silencer/suppressor, it was for an airgun.
I still want to know if there are public records or news reports about what happened to BOA. I would find it hard to believe that they were forced to close business (permanently), fined, or jailed without trial. On the other hand, I would readily believe that they had tools seized, products seized, and had their shop closed down (during investigation) which in itself could cause the collapse of their business.
Also, Smart Parts did exactly what Bill Mills asked the ATF about (The SP-8 Stealth Barrel kit, a shroud around a ported barrel) and the ATF never went after them. I suspect the reason was that they couldn't be threatened into closure.
Notbrian- there is some similarity with at least the first gen Apex models in that the bottom half has ridges that probably function somewhat as a suppressor but, since the rubber ramp provides a smooth path on the upper interior, it would detract from any effect. In BT's case, they probably concluded that their intent was clear (for backspinning).