I doubt that the pilot could be knocked out by accidental contact with a camera, and highly unlikely there was intentional interference.
I’m wondering if there was accidental manipulation of the controls by the front seat passenger. Say, for whatever reason, the pilot has to make the steep right turn. The passenger could have inadvertently put pressure on one of the rudder pedals ( the yoke is throw-over), either but turning his torso to the right to watch or photograph out the window. Rotating the torso to the right usually causes, involuntarily, the right foot to push down. Alternatively, the passenger, unused to steep banking, tries to maintain a vertical posture, with a similar result, pushing on the right leg.
The pilot enters a steep bank, 60 or more degrees to the right, the passenger “applies” right rudder.
Of course, only speculation of possibilities, but no further stretched than the knockout theory. It also depends if the right side rudder pedals were operational.