I mean, if a board member sees issues around them, they are still only one person.

This gives them the power that they should have been able to utilize when they were on it. Plus, I'd bet she assumed it will likely succeed and it's probably better optics to side with the employees than to double down. That said, I am confused about this portion:

We, the undersigned, may choose to resign from OpenAI and join the newly announced Microsoft subsidiary run by Sam Altman and Greg Brockman. Microsoft has assured us that there are positions for all OpenAI employees at this new subsidiary should we choose to join. We will take this step imminently, unless all current board members resign, and the board appoints two new lead independent directors, such as Bret Taylor and Will Hurd, and reinstates Sam Altman and Greg Brockman.

Signed the reinstatement after being the coordinator for the coup is definitely odd, lol