Legally, your are wrong.
You said: "-- If the 'system' is unconstitutional --".
The legality of the system being used to deprive him of his right to keep a machine gun is a clear violation of the 2nd Amendment, and is being challenged on that basis.
Obviously, you agree with the feds that machine guns can 'legally' be prohibited. -- Why?
You have a reading comprehension problem. You have no standing to adjudicate whether or not something is unconstitutional. That authority has been vested in the Judicial Branch of Government.
Weird 'answer', as I've never claimed to have "standing".
Whether the '34 fed firearms 'Act' is constitutional is the issue being challenged. -- And yes, the authority to decide that issue has been vested in the Judicial Branch [Supreme Court] of the US Government.
Obviously, you agree with the feds that machine guns can 'legally' be prohibited. -- Why is that?