What snow job? If the QCCA contract specifies extending to 20 hours with no question, why was there a problem going to 19:45?
Cabin crew should be aware that Tech Crew will not go past 20 hours on a four pilot crew as it is against the CAO's and hence is against the law, and a consequence the aircraft ceases to be insured in the event of an accident. I am guessing that is why a diversion to BNE was being considered. 20 hours is it.
Maybe that should be more widely disseminated.