Everyone who has paid a tax stamp and asked the government for permission to own a suppressor, SBR or SBS have created the precedent for registration of whatever the government wants to legislatively move to the NFA list.
They will use the argument that an "assault rifle" or braced pistol is for all intents and purposes just as dangerous as a SBR or SBS. Everyone who has a stamp for one of those has conceded that doing so does not infringe on their 2nd amendment rights.
I hear the same argument with a WC license. My kids tell me now the government knows I carry/have a gun. Well they know I own guns if:
I buy ammunition
Belong to the NRA
Buy a hunting license
Fill out a form 4473 to buy a rifle/pistol/shotgun
Use this site -- don't think they are not watching and monitoring either actively or passively
Send photos of a successful hunting trip
Belong to a gun club
There is no where to hide. So I enjoy what I have while I have it -- keep my powder dry and watch the skyline....
JMHO