And the actual licensing agreement between OpenAI and Microsoft isn't public, is it?
The reporting on this is so bad and contradictory. Without knowing for sure what these documents actually say, it's impossible to speak authoritatively about what's going on and how it will shake out.
That said, generally a majority member / partner can't just arbitrarily screw over minority members. Both LPs and LLCs are governed by agreements and statutory duties that protect minority members. These include duties of good faith, care, and loyalty. Majority partners/members must adhere to these principles, failing which minority members have legal recourse. There's a legal framework in place to prevent the majority from unfairly disadvantaging minority members.