I would definitely say the board screwed up.
https://www.forbes.com/sites/alexkonrad/2023/11/17/openai-in...
The board has no responsibility to Microsoft whatsoever regarding this. Sam Altman structured it this way himself. Not to say that the board didn't screw up.
Between Bing, o365, etc. etc. etc. it's possibly they could recoup all of the value of their investment and more. At the very least it is a significant minimization of the downside.