Place vehicle and some units. Name vehicle a1 and units u1, u2, u3, etc. Run u1 hideObject true; u1 enableSimulation false. Unit is hidden and no longer simulates. Then run u1 moveincargo a1, notice unit is unhidden and simulates. Run Run u1 hideObject true; u1 enableSimulation false since unit is in vehicle and the unit is not hidden and does not halt simulation.
This is true for disableAI commands as well. Mounted units will fire from vehicle (MH-9 Hummingbird in this example) even if disableAI commands are ran on u1.