THE CAPTAIN, HOWEVER HAS THE SOLE DISCRETION TO EXTEND A DUTY PERIOD BY A MAXIMUM OF 3 HOURS, PROVIDED HE BELIEVES THE FLIGHT CAN BE COMPLETED SAFELY!
With this statement in "bold" letters it gives me an idea that the decision was a very "one-sided" one that the Captain demanded instead of asked in a "humane" way, that was all that this crew needed to get there "moer-meters" stripped, and thus resorted to this "legal-loop-hole" to refuse to do the duty.
I am sure that had the situation been put across more diplomatically and in a sense of "team-work" the outcome might have been different.
CRM ..thats my humble opnion.....or possible lack of "tact there-of