Are you kidding me , mate!??
Is that a joke or are you serious?!We never let CA take control of aircraft nor even seat in pilot seats (only exception as many Operator's SOP, when some flight crew leave the cockpit to go to the toilet)!!
Not even take communication!
I think what AE had in mind is are deadheading crew ever asked/allowed to take seat in row 0 or take control of the aircraft ;-)