Thanks Claret,
All good points. What I had in mind was more re the first diversion to Melbourne; my thinking being that if the aircraft had been closer, it could have recovered to Sydney more quickly and so made the curfew.
Unloading at any of the airfields I mentioned would've been difficult as it was an international flight and those fields don't have customs facilities. And it's also true that the JC drivers would've been more familiar with MEL than the others.
The broader point is of course the pedantic application of the curfew.
Thanks guys