A lawyer could argue that three holes lined up here
I. Decision not to carry alternate fuel
II Weather at NI below minima. Weather there is notoriously fickle.
III. Apparent failure of pilot to be aware of weather, and so proceeded past PNR. It appears Nadi passed on incorrect ceiling. It is not clear if pilot received amended weather. Again, air services in the South Pacific are not infallible.
There are a lot of additional issues, but these are the 3 core issues directly related to this crash.
Of these three holes, the only one within the domain of the operator and / or regulator is that of alternate fuel. They have no control over the other variables. Which makes it all the more critical to manage the issue of alternate fuel. Which means the issue of aerial work or charter one of central significance.