So am I reading that if a passenger pays for a first-class seat or a business-class seat (this is speaking generally and not about this particular incident) and is asked to move to a lower class because pilots need to be transported for their duty and it's in their contract to be carried in first or business (as the case may be) the passenger is obliged to do so because the pilot's contract with his/her airline employer stipulates such a class of travel in the circumstances? Hasn't the passenger also entered into a contract with the airline to fly business or first (whichever he/she booked)?
Any company worth its salt will block off crew seats well in advance, providing they have notice, crew movements are often scheduled and can be easily planned for without upsetting anyone.