Maybe it has to do with them wanting to get rich by selling their shares - my understanding is there was an ongoing process to get that happening [1].
If Altman is out of the picture, it looks like Microsoft will assimilate a lot of OpenAI into a separate organisation and OpenAI's shares might become worthless.
[1] https://www.financemagnates.com/fintech/openai-in-talks-to-s...