We had the whole thing - including the JV - reversed in court in spite of them having the legal right to do all this. The reason: the judge was sympathetic to the argument that apparently the JV was a sham created just to gain access to our code. Counterparty was admonished, a notary public that had failed their duty to act as an independent got the most thorough ear washing that I've ever seen in a court and we got awarded damages + legal fees.
What is legal, what you can do and what will stand up are not always the same thing. Intent matters. And what also really matters is what OpenAI's bylaws really say and to what extent the non-profit's board members exercised their duty to protect the interests of the parties who weren't consulted and who did not get to vote. This so called duty of care - here in NL, not sure what the American term is - can weigh quite heavily.