It’s only for colleges and universities. Here’s the actual language, but my personal opinion is that it’s self defeating to use the exemption to avoid becoming members of Tripoli or NAR and proceeding through their certification levels. Tripoli membership for students is only $30 for the first year and $20 for renewals. For that you get insurance, access to launch sites with FAA waivers, and access to programs like the Tripoli Mentoring Program, which allows youths aged 12-17 out on the high power range with their mentors.
Here’s the NFPA 1127 exception:
1.3.3 This code shall not apply to the design, construction, production, manufacture, fabrication, maintenance, launch, flight, test, operation, use, or other activity connected with a rocket or rocket motor where carried out or engaged in by the following entities:
(1) National, state, or local government
(2) An individual, a firm, a partnership, a joint venture, a
corporation, or other business entity engaged as a licensed business in the research, development, production, testing, maintenance, or supply of rockets, rocket motors, rocket propellant chemicals, or rocket components or parts
(3) College or university