From CNN - edition.cnn.com/2025/02/26/australia/qatar-airways-flight-dead-passenger-body-intl-hnk/index.html
Another passenger offered Colin (the wife) an empty seat across the aisle from Ring, where she sat for the rest of the flight.
This indeed sounds like he could have got out! Perhaps the crew thought he and his wife would prefer to be across the aisle from each other than sitting in different areas.
After the flight landed, Ring said passengers in his area were told to stay put until ambulance workers and police officers arrived to remove the body. “I can’t believe they told us to stay,” he said, adding he was present when ambulance officers pulled away the blanket.
He also seems offended that the body was removed before nearby passengers could get off, but I am sure that is protocol as it would be awful if someone, say, knocked the body with a suitcase etc.