The link above to "Qantas Source " shows two QF 737's diverted to Canberra at about the same time that night. I imagine if the JC aircraft had the fuel then QF may have preferred them in Melbourne because of that. At the end of the day it doesn't matter why they went there really, what matters is the cost to Australia of ASA dropping the ball and not landing aircraft when the airfield was open.
Is anyone going to stand up and say " yeah that was crap, we'll do better next month" .