Thanks Sarcs
Given the ATSB states that they were holding:
During the cruise, the weather at Adelaide deteriorated and the
aircraft commenced an extended holding pattern. While holding, the crew declared a fuel emergency and diverted to Mildura, Victoria.
The Mildura forecast takes on a whole new importance. I imagine that had their been any doubt about the mildura forecast then they would have continued to Adelaide and autolanded with more confidence.