I don't think it is ambiguous.
The pax wasn't strapped in properly, his helmet was loose if not unfastened altogether and he had no way of communicating with the pilot with the mask not fitted. He was already severely nervous before the flight.
He's then properly alarmed by an abrupt application of 4g and a rocket-like climb, and upon the -.6g pushover at the top left his seat due to the loose straps, probably felt the helmet coming off and in a panic grabbed whatever he could find to pull himself back into his seat.
Lucky he wasn't injured more seriously as his ejection posture must have been awful.
French swiss cheese must have much larger holes in it than we ever imagined.