Charon
I'm guessing that, having allowed a second-best situation to develop, both the QF and
VB crews thought that Mildura was a good option. Certainly a paradise compared to ETOPS planned alternates like Cold Bay, Adak, Shemya, Petropavlosk, Anadyr and Magadan in winter.
The question you should have asked:
"At what point in the flight did it appear that Adelaide might well go bad and that anywhere else nearby (same high pressure, lioght breeze, small dew point/dry bulb split) would also likely go bad (or at least risk that) too. At that point was a diversion to MEL available?"
I would find that question interesting for command training courses and LOFT exercises etc.
But then I scare easily.
A