Weird... Ilya decides one way then changes his mind. Helen and Tasha vote one way and had the votes to prevent any changes, but then for some reason agreed to leave the board. Adam votes one way then changes his mind. So many mysteries.
Ilya and Adam switched because they lost, and their goal wasn't to nuke OpenAI, simply to remove Sam. Helen and Tasha had the votes to prevent Sam Altman from returning as CEO, but not the votes to prevent the employees from fleeing to Microsoft, which Helen and Tasha see as the worst possible outcome.
There's some game theory going on... They're just trying to pick the winning side. I guess most people at OpenAI supported Sam, because they thought Sam would win at the end, although they wouldn't necessarily want him to win.
If the Sama faction got Ilya and Adam (maybe with promise of heading the new board), Helen and Tasha have nothing to stand on and no incentive to keep fighting.