I’ve seen boards hinder nonprofits from executing on the mission plenty of times, usually out of ego or general fecklessness.
I wouldn’t assume that boards care about the mission more than the employees. Employees are the ones signing up to implement it, board members are often just in it for status and are total dilettantes.
I think in this case there’s a lot of signs pointing to the board feeling that their status was threatened more than anything. If their reasoning is that releasing ChatGPT without their permission was “unsafe,” give me a break.