Who knows...the start of a kindler, gentler, more logical and reasonable ATF?
No they realized the Supreme Court decision applied to all such firearms based on the details of the actual legal challenges in the Thompson case.
The details of the end ruling are only part of the story, the arguments actually being addressed to bring it to the SCOTUS, combined with the SCOTUS ruling. They even spoke positively of the utility of such a firearm that could go back and forth between legal pistol and rifle configurations.
Absolutely it did not just apply to a single firearm, as was the ATF's crazy interpretation. That is like saying Brown v. Board of Education only applied to that one school, or one county. The Supreme Court rulings never have worked like that, they address the law behind the specific situation, the contested legal issue that took it from the lower courts to them, and so the ATF's conclusion was flipping the bird to the Supreme Court.
The ATF's contrary view would have meant they could readily lose in court if challenged.
For some reason they came to terms with the error of their ways, perhaps in light of the pro-gun momentum across the USA, and instead of sticking with an interpretation in direct opposition to the SCOTUS (by saying SCOTUS meant something else, so 'we are actually just doing what they said') changed their interpretations to comply with SCOTUS.
Now the irony is I think their interpretation which was in contradiction to the SCOTUS ruling kept things more simple across the board. They wanted things to stay simple. It meant less freedom, made no real sense as a restriction, but certainly made for easier enforcement. Assembling a long gun made a long gun, and anything made after was something made from a long gun, an NFA item no matter how it started out originally.
However in modern times with virtually all commercial guns papered and traceable to the manufacturer and/or 4473 to determine what they originally were, enforcement is still quite simple. It's not like someone can claim it was a pistol if it never was.
The SCOTUS may or may not have been right in their interpretation of the laws in question and Thompson sales perhaps shouldn't have been deemed acceptable, I don't know, but it was their clear decision. The ATF's interpretation was certainly in clear and direct violation of the ruling SCOTUS did make.
They didn't like the implications and chose to ignore the SCOTUS ruling by saying their loss in court actually meant what they were arguing in court all along, but only for every single other firearm. Essentially saying they won anyways, refusing to accept the loss.
I imagine SCOTUS would not be too happy dealing with them again on the same issue because the Agency decided to say that the SCOTUS actually meant what the ATF had wanted to be the case all along, lost their argument in court, and then essentially refused to lose by stating it just applied to one gun. I think such clear childish opposition and refusing to accept the SCOTUS decision would have pissed the SCOTUS off.
They came to their senses, ceased violating a SCOTUS ruling, and now we all have the freedom the Thompson case intended many years prior. I don't know if I would call that kinder and gentler or stemming from a more pro-gun attitude, but I am glad they made that decision.
Thanks ATF.