In FlightSimulator.cfg edit this section to:
[DynamicHeadMovement]
LonAccelOnHeadLon=0.00000
LonAccelOnHeadPitch=0.000000
RollAccelOnHeadLat=0.000000
YawAccelOnHeadLat=0.000000
RollAccelOnHeadRoll=0.000000
MaxHeadAngle=0.000000
MaxHeadOffset=0.000000
HeadMoveTimeConstant=1.000000
The involuntary head movement goes away relative to the plane/panel.