>

Doubt they'll be able to do anything after EPA v. West Virginia. They'll need an act of congress to enact it.
I give it 3 months before the SC tells them no. >

Under Bruen & Heller, this should not hold up in court, but it could take years.  
However, considering that the ATF changing an interpretation of a definition (that conflicts with their previous interpretation of that same, unchanged definition) could make millions of people felons I think an injunction is likely. >

How many mass/school shootings have been committed with a pistol using a “stabilizing brace”? Or even just how many firearm-related homicides in general have been committed with one? >

Until I hear otherwise, I’ll assume the answer is zero.  Examples would have been trotted out had there been.  This rule is pure theater, and does nothing to improve public safety. >

Bingo. But hey, I get to register a lower as a sbr for free for a limited time, though.