The NFA, or National Firearms Act is literally an Act of Congress. Seems a little strange that members of congress, the group responsible for the NFA would ask the president to do it. Obviously they don't think that they have the votes to do it the proper way. The founders are rolling in their graves.
They didn't have the votes then, either. They were afraid that no one would go for an infringement upon rights guaranteed by the 2nd Amendment. That's why they made it a tax.
But I get your point, and I agree.
"Posterity! you will never know how much it cost the present generation to preserve your freedom! I hope you will make a good use of it. If you do not, I shall repent in Heaven that I ever took half the pains to preserve it."
- John Adams