CX, just to clear up what is possible here; LAX-AKL would be a three pilot crew. Max planned duty hours for such a crew is 14 hours with a contractual elective extension to 16 hours.
Depending on where the diversion to HNL took place from, (and depending if the rest of the story is true) then it may have been possible to fly to AKL in over 14 hours but under 16 duty hours which would have required the crew to agree.
I have zero info on this story but if the crew had been faced with a two sector, all night flight to 16 hours then I can see why they would have had reservations.
For the record, sector times are LAX-HNL (straight line) 4.35 hours.
HNL-AKL 7.35 hour.
You can add 1.5 hours pre and post flight duties plus taxi-time, plus any time spent on the ground at HNL to that.