This is an excerpt from FAA regs for RVSM,
Note that number four clearly exempts non RVSM aircraft that are climbing or descending through RVSM without any planned level off’s:
Subject to FAA approval and clearance, the following categories of non-RVSM aircraft may operate in domestic U.S. - Department of Defense (DoD) aircraft.
- Flights conducted for aircraft certification and development purposes.
- Active air ambulance flights utilizing a “MEDEVAC” call sign.
- Aircraft climbing/descending through RVSM flight levels (without intermediate level off) to/from FLs above RVSM airspace (Policies for these flights are detailed in paragraph 4-6-11, Non-RVSM Aircraft Requesting Climb to and Descent from Flight Levels Above RVSM Airspace Without Intermediate Level Off.
- Foreign State (government) aircraft.