Vette may have brought it into common parlance, but the term existed in scientific circles before he began his investigation. The problem with your rigid interpretation of NZCA's rule is that it was knowingly flouted by ANZ on a regular basis and a dispensation to break it was given verbally at the very briefing attended by the crew.
To say they broke the CAA regulation in itself may arguably be technically correct, but in real-world terms the fact that they were given a dispensation to break it by a senior airline official means - to my mind - that the responsibility lies higher up the chain than the PIC on that occasion.
In the end the original finding of "pilot error" was based on certain assumptions that ranged from the dubious (that the briefed track went straight over Erebus) to the dead wrong (that they were in cloud when they crashed). Evidence that had as much potential to vindicate that conclusion as it did to scupper it was misplaced or destroyed - why?