With all this talk about diversions, my understanding is that Noumea may not have been an option. The French authorities had earlier that year (Feb 2009) banned the operator from flying into Noumea due to non-compliance with the EU regulations - no TCAS II, no EGPWS. The operator was in the process of addressing this and had updated the aircraft systems, but the pilots had not yet completed training in its use.
Sure he could (? should) have diverted there prior to PNR. With full fuel he may have even been able to reach Noumea at TOD Norfolk - when he definitely knew weather was below landing minima.
However I wonder if the operators difficult history at Noumea played a role in the pilot's decision making. Did he press on to Norfolk and descend into Norfolk thinking there would be trouble if he went to Noumea?