From some rumbling of the not too distant past comes the remembrance that Captain's discretion may be applied by him in respect of his crew. The crew must agree to the application of discretion for it to be applied. Such agreement, whilst perhaps advisable, is not mandatory. The crews' decision does not have to be unanimous in that so long as minimum crew for safe and legal flight agree to extend a flight duty period into Captain's discretion, the aircraft may depart having left behind any crew who did not agree to extend into discretion.
If that is the case, then the crew were perfectly within their rights in refusing to extend, especially bearing in mind that the flight had not yet left its departure point. Discretion is primarily designed to enable a flight to continue in the event of unforeseen circumstances occurring down route. It may not be used for the purposes of planning a flight.
That said, it is to be hoped that the cabin crew passed a very uncomfortable night on the airport floor rather than returning to the party.
