If he could have done the brake check without riding on public roads, he was right - no M endorsement required. That aside, I'm witchu - no M, no ride.
I'm even worse, if they want to ride my bike then I go to a different inspection place. It is either that, or they can observe me doing whatever they want me to do in order to prove the vehicle's safety.
Lucky for me I have a place where I can bring them a bike on a trailer and they won't even ask me to unstrap it.