Ann: Good Oil 2016 - Conference Presentation-STX.AX, page-47

Seems to me, from PSI's comments, that there was reason enough to question some of DW's decisions on technical grounds alone. And with the company moving from development to commercialization, possibly bringing in new money to finish off the pilot phase properly, it made sense to replace him.
Or to put it another way, DW's resignation/dismissal has nothing to do with internal scandal or the failure of the tenement. Rather a rational decision by the board to replace him.
Just pointing this out as some people seemed to have reacted to DW's dismissal as though it were the break-glass option (i.e. a portend of imminent disaster).