Folks,
If you look back through the archives, we have gone through all this before.
In particular, in one post, long ago, I gave a brief history of all the close go fuel exhaustion cases, and several "wents", to airline aircraft, that resulted in the ICAO standard of 30 minutes fixed final reserve.
Briefly, it is to ensure, based on all the "order of accuracy" issues, that "on the day", you have at least some fuel remaining at touchdown, so that any or all engines are "Turning and(or) burning".
This 30 minutes is NOT flight or holding fuel.
As usual, CASA have made a complete pigs ear out of a regulatory issue that should largely be handled as an educational matter, before the event, not a strict liability criminal matter, after the event.
Tootle pip!!