That's a good question, and I agree it was a clever design. I don't know that there is a way to modify the org structure to prevent what happened. As much as I dislike them, a clear non-compete clause after the structure was in place might have helped, but I'm not sure that's even an option in CA. And having employees re-sign for noncompete would be fraught itself (better from the start). But this does seem like the most relevant application of non-compete. I'm not a lawyer and I'm sure they had top notch lawyers review the structure. If OpenAI played the non-compete card it wouldn't make retention easier if employees were willing to walk (they wouldn't exactly have trouble finding jobs anywhere). Do you know of anything that might have prevented it?
Well, if you squint a little bit, this all looks kind of like a military coup. Through the cultivation of personal loyalty in his ranks, General Altman became able to ignore orders, cross the Rubicon, and subjugate the senate. It's an old but common story.
I point out this similarity because I suspect that the corporate solution to such "coups" will mirror the government solution: checks and balances. You build a system which functions by virtue of power conflicts rather than trying to prevent them. I won't pretend to know how such a thing could be implemented in practice, however.
Out of curiousity, with the benefit of hindsight; what would you have tried doing differently to prevent such a coup?