Don't they only have to hide the truth from one person? Altman and Brockman were ousted. The only other person on the board from OpenAI is the Chief Scientist, and I doubt he's that involved in the business-end of things.

Edit: Also, yes, it's hard to sweep things under the rug. We don't know the timeline of events, and we're seeing an instance where Altman failed to hide something.