Quite often with a full load and a wet runway expected in ZQN you CAN'T carry enough fuel for the return to AKL due landing wieght considerations. Your options are CHC, DUD and INV. On that day only CHC was available. I don't see what this story proves, every airline gets caught be the weather every now and then, see the Air NZ story from last year.
Trapped passengers want investigation into 'nightmare' journey - National News | TVNZ