4 pages and he is still argueing the point.
Do not confuse "a flight" with " in flight".
From ICAO
Pilot-in-command. The pilot designated by the operator, or in the case of general aviation, the owner, as being in command and charged with the safe conduct of a flight.
2.4 Authority of pilot-in-command of an aircraft
The pilot-in-command of an aircraft shall have final authority as to the disposition of the aircraft while in command.
Band a Lot, Command of the aircraft would be as stated before is at time of pre flight preparations including boarding fuelling loading etc.