The OpenAI staff are literally some of the most employable folks on earth; if they have a problem with the new mission it's incredibly easy for them to leave and find something else.
Additionally, I think there's a reason to give Sam the benefit of the doubt. YC has made multiple risky bets that were in line with their stated mission rather than a clear profit motive. For example, adding nonprofits to the batch and supporting UBI research.
Their's nothing wrong with having a profit motive or using the upsides of capitalism to further their goals.