Well I guess there is no need for an investigation as you fellas seem to have it all worked out.
A few times on the way to MEL I have seen the CAVOK weather forecast we left with, change to Tempo fog. Luckily flight watch did not inform us (but playing with ACARS did) as what you don't know won't hurt you right? Guess when you fly half a day to end up somewhere things can change. Was this the case?
I have also left ADL to return to MEL after diverting to find I had to hold forever as all the domestic traffic that had been holding recovered. Perhaps they left within the limits and were caught short when they arrived. Should they have just turned off the engines at time expire time? Perhaps they forgot to mention that they wanted the GPS approach the required 5hrs before arrival, and the approach controller cracked the Sh@ts again and put them into the hold?
Could have been a million reasons why this happened. I was not there and have no idea why, just like you fellas don't. But I am sure that the crew would have made the best decision they could have at the time, with the info they had, and all of this without any assistance from Flight ops. Because we all know that flight ops will never help when there is a good chance that someone will need to be held accountable somewhere.
Don