Had this discussion a few weeks ago with a 30+ yr 744 captain and the issue of an earlier B767 contemplating a ditching over there some years back. Same circumstances.
Was agreed that while minimum fuel was offered, they were never under any "extreme pressure" to not uplift more if they felt the need.
Also I noted he was quite plain about .....Autoland, and very carefully, even in Perth is a much better option than any other alternative when the fuel is low.
I do think for the cost V risk Sydney and Perth should have CATIII. Seems to be a few diversions each year in both places, and Melbourne. One day it may well go pear shaped on someone.
J