Sorry to burst your bubble Old rope but it's a 2 crew operation these days, not like back in WW2 eh ?
Most of the guys I fly with would listen if the effo had an objection to a jump seat rider and most ask as a matter of course anyway.
And FWIW, probably a good chance I have approved/disapproved more
JS's than you've had hot breakfasts, we did'nt all sit in the
JS/RHS for 10 years in CX.