At the moment, it's more like owning something the ATF might rule to be an SBR. So far, they've only gone after the Honey Badger, not any of Q's other brace equipped AR platform pistols, not any brace equipped AR platform pistol offered by any other manufacturer. I strongly believe that, depending on how the election goes, this stupid decision will either be reversed and those responsible for it canned or, it will be the least of any gun owning American's worries.
As for yours, since you added the brace you could simply remove it till this nonsense gets sorted out. Unless the ATF has changed that rule too, neither a handgun with provision for mounting a shoulder stock or a shoulder stock for that handgun was considered an NFA item. They only became one if you attached the stock to the handgun.