If the autopilot has finished trimming the aircraft and the a/p kicks off, the aircraft pitch shouldn't change and neither will the yoke. The a/p will trim until the control force is zero. If you disconnected the a/p while it was trying to trim the aircraft, then the pitch would change and the yoke would move. You would move the yoke in the opposite direction to counter the pitch from the untrimmed condition. Example... the a/p is trimming down to overcome an out of trim nose-high condition. If you disconnect the autopilot, you're going to move the yoke forward to overcome the nose high out of trim condition. So, basically, he may have made another mistake... not guarding the controls during an ILS. When the stick shaker turned on and the autopilot disconnected, the airplane might not have been under positive control. Obviously, we can't see what was going on in the cockpit, but the FDR video is very telling.