A Corporate Contract Pilot resigned after the Captain flew the aircraft in RVSM airspace with the autopilot inoperative.

Narrative

This flight was conducted in RVSM airspace without an operative altitude control system. On the way to the airport; PIC informs me (SIC) the aircraft autopilot systems are not working. PIC says he will put it in the logbook. I remind him that the autopilot is required to fly at our planned flight level. He rethinks the logbook comment and says he will enter it after we land. The flight went as planned at cruise flight level with no traffic conflicts and only very minor altitude excursions. The PIC hand flew the aircraft from the left seat for most of the flight. I flew some from the right seat. Except for the autopilot issue; the flight was uneventful. For the next couple of days; I thought about this flight quite a bit. Could I have been more assertive in suggesting we pull out the MEL? Yes. Should I have been a little more assertive about staying out of RVSM airspace? Yes. I also feel I was in an awkward position in that I was a contract pilot. As a contract pilot; one wants to get along and not make any waves. One is best served by 'getting along' with the operation. The consequences of being a little too conservative can result in not getting work. I think this played a part in my behavior on this trip. As I mentioned; I thought about these things a good deal after the trip. When I connected other aspects of the operation with the fact that this was not the first time this operator had exposed me to possible violation; I decided it would not happen again. Shortly after; I effectively resigned informing them I would no longer be available to fly their aircraft.