The pilot has to have regard to these matters but doesn't have to do anything specific about them.
"have regard but not do anything" - I find that faintly ridiculous, and wouldn't want to walk into court with that as my defense. In any case I disagree, but hey-ho.
he still ends up with insufficient fuel to make it to somewhere else after being unable to land at YSNF.
I don't think anyone disputes that. The long sector inbound to Norfolk meant that the destination was (under ICAO Annex 6) a "remote aerodrome", in that the aircraft couldn't carry enough fuel for an alternate. Under Australian rules at the time, and as an airwork flight, that was legal. International Authorities generally require two hours holding for a remote aerodrome and don't classify Air Ambo as airwork. In that sense the pilot was operating under a regularory system which was less safe than international standards.