I'm not surprised, Polymer80 probably doesn't know what it wants to do just yet. It has only 1 day since they won the injunction.
While we have fixated on who is protected by the injunction, it is still a good ruling on multiple levels. The judge is following Bruin style logic, is throwing out Chevron deference, and did pretty much deliver a good smack-down to the ATF in my humble opinion. By issuing the injunction, he is telling the ATF that what they are doing is not legal on multiple levels, violating several parts of the Constitution at the same time. Yes, it is a preliminary injunction. There hasn't been a trial. But, to paraphrase it, the judge pretty much told the ATF that they are going to loose the trial.
Now the ball is in the ATF's court. They already tried to have the case dismissed, and failed, now their choices are: 1.) Appeal the injunction, which will further piss off the judge, and is just a short term solution. 2.) Accept the injunction for the moment and try to win the trial. 3.) Settle the suit, which means removing the regulation, paying the plantiff's damages, and avoid the trial.
My guess will be they will go for option 1 followed by option 3. None are good options from the ATF's point of view. They are too used to not having to defend their actions.