Heritage had approached another potential director before Pringle, who had turned the offer down.
The company submitted that "recruitment was challenging", and that "suitable candidates were deterred from taking on a directorship with the company in light of the Pike River mine disaster on the West Coast, where the directors and senior management face substantial consequences and other recent decisions relating to the potential liability of directors."
NZX submitted Heritage should have known of a possible departure from the board as Grigor had missed some meetings and had signalled he might be unable to continue.
The tribunal decision said the Pike River disaster and other recent decisions on director liability were "all the more reason to ensure that the board has the requisite number of independent directors at all times."
Separately, Heritage yesterday announced the appointment of lan (Doug) Buerger and Paul Griffin to the Heritage Gold board, replacing Peter Atkinson and Geoff Hill.
It also extended the period for its share purchase plan offer to May 16, following a requirement to issue replacement application forms.