Joshua Prince is a legitimately cool guy, my boss and he are good friends.
My sticking point seems to be this: Say a Trust is allowed to Form 1 a Machinegun, as they are not a person as defined by the GCA. The Approved Form 1 comes back. The Trustee converts the firearm into a machinegun on behalf of the trust. If we go by the logic of the letter, is a trustee, as an individual, still prohibited from possession of the machinegun not registered before the effective date of the subtitle? I have more reading to do, but it is certainly an interesting one. It would be a heck of a thing if the trust could legally make the machinegun, but no person could physically possess the thing.
I haven't parsed the language or given it much thought, but why would this be analytically distinguishable from the physical possession of a suppressor by the trustee of an NFA trust?