Coke, hypothetical.
Regarding a pilot, it could only occur in high level cruise; shall we say a post-curry moment. All the crew would be on 100% oxygen. An abandonment event might have been an electrical failure as happened to a Mk 1 Vulcan near Chicago. As the event was abt height I guess the crew would assist the pilot back to his seat.
In the event of an emergency at low level the crew member not in his seat would be one of the rear crew or a checker. Should the unseated crewman not be wearing his bone dome and parachute then probably tough. My job was to open the door and I would not have delayed. Once the door was open my job was to gety out of the way and that meant jumping.