It should be. But it is unfortunately not. All they have to do is change the rule so that you have to do something like pay $1,000 tax every year to maintain the stamp. Not saying they will or that it would work well. But it's done in lots of industries all the time. Hopefully this causes enough of an uproar to stop the bullshit.
What I'm hoping to see is that, since the ATF issued rulings in the past that braces are legal, they have to confine this issue to Q AND issue clear guidelines on what differentiates a pistol from an SBR.