Let me play devil's advocate here so we can be prepared for the inevitable counter-arguments of the enemy:
Hunters can wear electronic hearing protection if they choose to do so, and therefore do not need suppressors to protect their hearing. The electronic hearing protection actually makes them hear better in the field. And it costs less than a suppressor.
The military can issue electronic hearing protection. Or it can issue suppressors (as it sometimes does); the law making suppressors difficult and expensive for civilians to get does not apply to the military, any more than any other gun control edict does.
I would not have framed this as a hearing protection issue. But the NRA has done a very good job considering the power the enemy wields, so I respect their judgment. I would argue that the edicts in the NFA are unreasonable and therefore illegal infringements on the 2nd Amendment. It is not incumbent on us to provide a reason to exercise a Constitutional right; it is incumbent on the proponents of the law to provide an overwhelming reason for any and all infringements on the right, and a case against suppressors simply does not meet that test.
The critical path is in exposing the lies used to convince people that suppressors meet a realistic test of reasonableness. And that will be hard to do, since what constitutes reasonable in this context has no definition, and so is essentially meaningless. That's why patriots really should be coming up with a realistic test of what really does constitute reasonable when it comes to an infringement on a Constitutional right. Until that's done, these things will all just be a matter of which side does a better job of promoting its argument, and the 2nd Amendment will be more a hurdle than a wall.
This argument being made is related to the sporting-use argument, and to me that argument is a dagger to the heart of the 2nd Amendment. All sporting-use language should be removed from all gun laws. Applying a sporting-use test to the 2nd Amendment is like applying an entertainment-use test to the 1st Amendment (i.e., does this news program that criticizes Obama have a legitimate entertainment purpose?). Sporting use language concedes the fundamental argument to the enemy.