Sure, but legal processes aren’t quick. I would assume they’re trying to be thorough in the process. Probably not a great sign they letting the rule stay but in theory it doesn’t actually do much. 80% manufacturers can still sell products. I can still buy an 80% or a 3d printer.
The real thing would be to just get a ruling to limit how they can change law through changing definitions. Same reason slapping down the bump stock was needed.
Also the issue there ruling on probably won’t actually be a 2a thing but about the rule making effectively side stepping the legislative proceess.
The change doesn’t really seem that great and there are years missing.
Also “Gun laws should be stricter” is too vague for the range of policies involved. When a gun control advocate says that they might mean bans. Someone else might be talking about opening up the NICS or want to improve the background checks somehow. There are also a lot of people who don’t actually know the existing laws and want “stricter laws” we already have.