I'm not really familiar with this specific case and you may very well be right that the ATF is overstepping. We already have multiple possible solutions to this

I'm not really familiar with this specific case and you may very well be right that the ATF is overstepping. We already have multiple possible solutions to this problem. Statutory interpretation, congressional approval of cabinet members, or congress passing a new law that eliminates that interpretation are all solutions that are designed into our system. Elections are also a solution to this, although they're probably a bit too coarse to solve individual regulatory issues. It is impossible to have an executive branch that doesn't interpret the law because the law is just a piece of paper. Determining what level of interpretation is okay is already a part of our system. There is no way to just revoke that power without just collapsing the government.