Keep in mind that the alphabet agencies are allowed to decide the details of implementation of new laws under their administration.

The BATF could (and likely would) expand on any vague 'exemption' in a law to include whatever groups of people they choose--or are ordered to favor. The out of control FDA and EPA do this kind of thing all the time.

This also means they can set cost prohibitive fees or any other rules to keep ordinary people from being able to protect themselves, even if the official legislative documents are silent on these issues.