We had similar up this way where a GA aircraft hit the hills in poor weather, pilot didn't complete his training to solo level but chose to fly, Both he and his wife were killed unfortunately. In this one an instructor signed him off and the pilot involved decided to fly the route.
My very limited information on this is along the lines that he achieved solo and was granted x/c at some time and the instructor is not with us to explain his reasoning. Seems x/c at least was not supported with his RAA flight times.
When I gained my certificate same person at RAA advised my gliding XC was not able to be transferred or recognised so had to jump all the hoops.
Thier are a small number of poor performance decisions identified by RAAus, one example is bfr done with instructor being separated by 400 or so kms at the time, over phone deal and there would be a few more I'd guess.
My belief is don't blame RAAus 100% and there is learnings from this.