In customer relations, it wasn't unheard of to deal with a down graded passenger because of flight crew rest. I remember dealing with a pax (High Value Gold Card) downgraded from FIRST to Club World because one FIRST seat was needed for flight crew rest. Very difficult to explain to the pax, especially when CW had about 30 spare seats on this flight but I guess it's in the agreement.
Something not quite right there. Theres never been an entitlement to a First class rest seat.