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.
Besides, even if you had an outstanding contract for $10bn, a judge would not pull a "well technically, you did say <X> even though that's absurd, so they get all the money and you get nothing."