It seems to crop up occasionally, see for example this Wellington Fund blog post that uses the phrase:
It is not time for high-stakes Boardroom poker, but that’s exactly what happened at easyhome (EH:TSX)... At least I assume that some Boardroom poker took place, since a majority of the easyhome Board of Directors resigned simultaneously, including one Director that had been there for merely eight weeks. According to the press release, five of the nine directors just up-and-left, leaving two independents, a 29% shareholder Chairman and a CEO/Director to manage the affairs of the company.
What does Boardroom poker usually mean?