The ATF is going to struggle under the Bruen ruling from the supreme court. It wouldn't surprise me to see them defeated on the FRT issue. That is what is monumentally frustrating with the ATF. They approve something as legal, and then when the politics change, so does their approval.
While I don't get the whole pistol brace/sbr issue, if you want to have an AR pistol, more power to you. I would rather pay the $200 tax and have an SBR and not have to worry with the ATF changing its mind.