I read it as saying that they were conflicted because they're both from the "highly ideological" Open Philanthropy; on a small board, having two people ideologically aligned seems precarious.
Ever seen a Catholic hospital with a Satan worshiper on the board?
If the mission of OpenAI and its reason for being created is to make sure AGI is kept in the public trust and not walled off by commercial forces then you’re not going to want people believing the opposite of that.