https://www.cnn.com/2019/10/11/us/ar-15-guns-law-atf-invs/index.htmlFederal authorities preferred to let Roh go free rather than have the ruling become final and potentially create case law that could have a crippling effect on the enforcement of gun laws, several sources familiar with the matter told CNN. Each requested anonymity due to the sensitive nature of the case and its possible implications.
The ruling would have done more than invalidate ATF's position on build parties, it would have held that AR lower receivers aren't firearms at all.
ATF abandoned it's case so that the ruling would not become final. So it is not binding precedent on anyone.
A future court might reach the same conclusion, or it might not. The only thing I am certain of is that in either case, somebody will be paying some lawyers a lot of money.