Originally Posted by
the810
The regulation doesn't require the airline to offer a choice of a downgrade or other options. The only requirement is to compensate passengers in case of a downgrade. Any other option, e.g. rebooking is provided on a voluntary basis.
You have a right for re-routing under comparable transport conditions i.e. same class.
You could try to argue that the flight was not "cancelled" when a passenger was unable to travel in the class of travel as booked, but you will be laughed out of the courtroom on multiple counts including spirit of the law and good old contract law.