“resulting technology will benefit the public and the corporation will seek to open source technology for the public benefit when applicable. The corporation is not organized for the private gain of any person"
I don't think it is going to be hard to show that they are doing something very different than what they said they were going to do.
The charter is not a contract with Musk. He has no more standing than you or I.
He has no ownership stake. He isn't a director or member of the organization. The thing he claims is a contract he's party to, isn't.
So, once again, I have absolutely zero idea if OpanAI can be held accountable for not following their charter or not, but if they do, anyone can raise a complaint, and since Musk did give them money to save dolphins or whatever, he may actually be considered the victim.