I usually try to avoid pulling the "every airplane is different" card, but in this case, I was amused to find this as the first passage of the "Electric Trim" section of the Baron's POH:
"Because there are several different models of autopilots and electric trim systems installed in Beech airplanes and different installations and switch positions are possible from airplane to airplane, it is essential that every owner/operator review his Airplane Flight Manual (AFM) Supplements and ensure that the supplements properly describe the autopilot and trim installations on his specific airplane"
In the case of the Baron Professional, this is the intended behavior, because the electric trim and autopilot actuators are powered from the avionics bus. I believe the logic being that, as the POH says a few lines later, "It is often difficult to distinguish an autopilot malfunction from an electric trim system malfunction. The safest course is to deactivate both."
Does my explanation make sense? If you know more detail about the typical installations with KFC-150's in Barons, please feel free to share! If you have any other questions, I'm always happy to answer too.
