I question if any board in history has explained itself with clarity and honesty. By my cynical lens they would never stoop to engage in virtues other than signalling.

I think it's possible that Sam had some secret plans involving deals with external companies, that the board learned about. They can't reveal that information without potentially damaging other businesses and becoming liable.

While Sam tried to make the impression that he doesn't know why he was fired, he didn't even try to deny the allegations that he was in talks with the Saudis to create a for profit AI hardware company.

I think you are right that Ilya didn't want to give out secret information to not open up himself to lawsuits.

Maybe for a company of 12-50 there would be more candid discussion internally, but over 100 and especially at OpenAI size (and with Microsoft involved) liability control is at the max. Moreover, if the Board thought the decision would help improve retention, then they would comment, but that's clearly not the case.

OpenAI is not a typical LLC or S/C-corp though, so the Board also has to overcome that conceptual hurdle.