It's not a stock. It's an arm brace. Per the text of the law, they are legally NOT a SBR. How you use something does change what it is. The government bans hammer. In the definition of the hammer ban, it says "designed or redesigned to drive in nails." If I "circumvent the law" by using a rock to drive in nails, the rocket doesn't morph into being the legal definition of a hammer, and I am still NOT in violation of the law. They will have to amend the law to encompass rocks (or the act of driving in a nail) if they want them to be covered by the hammer ban law.
The ATF is writing law for the political purposes. The Biden administration told to ban braces, and they choose to follow orders. Some people foolishly believe violating the "spirit" of a law is the equivalent to violating the text of the law. It is not. Seem that the plain text of the law and words have no meaning anymore. It's "spirit" and "feelings" that take precedent. They are de facto creating new law when they clearly are interpreting the text of the law to mean something it doesn't say. If the law says knife with a 3" blade or less is legal, and an unelected state agency unilaterally interpret and deicides that a knife with a 3.000000000000001" blade should also be covered by the original law, then they de facto changed or rewritten the law. The original law now means something other than what it states.
A pistol brace wasn't designed, made or remade, and intended to be fired from the shoulder by the manufacturer. How the end user deicides to use it isn't addressed in current law therefore whatever isn't explicitly illegal is legal by default. Pistol braces are CLEARLY legal per text of the law. Again, there is nothing in the text of the Federal NFA law that has the word "misuse" in it with regards to defining what a rifle is. That is, it's perfectly LEGAL for the end user to misuse, "skirt the law," or use a "loophole" by shouldering a pistol with a brace on it as braces were NOT designed, made/manufactured, and intended to be used as a stock! This is just plan logic and common-sense IMHO.
I'm surprised by how many gun owners on this forum are using illogical antigun rhetoric and reasonings to support the idea that the ATF is right, bump stocks and braces should have never been approved, and/or they are NFA items...