For a promise to be enforceable in contract, it has to be definitive. There's nothing definitive here.
For a representation to be fraudulent, it has to be false or misleading and relied upon as material. Courts don't treat a later change of heart as making earlier statement false, and since Altman arguably knew less than Musk at the time, it's unlikely to be material.
More generally, investors lose all the time, and early minority investors know they can be re-structured out. These investments are effectively not enforced by law but by reputation: if you screw an investor, you'll lose access to other investors (unless your investor tribe is, well, tribal).
The detail and delay that evolved in law for the sake of truth and legitimacy is now being deployed for the sake of capturing attention and establishing reputation.
Musk's investment in twitter has been a catastrophe from an investment and business standpoint, but has amplified his icon status with king-maker aspects through control of attention in our attention-based economy and politics. If he can lead the charge against AI, he can capture a new fear and resentment franchise that will last for generations.
Hence: posturing.
We burrowing mammals can hope the dinosaurs fighting might make life quieter for us, but that's just hope.
This doesn't make any sense: https://en.wikipedia.org/wiki/XAI_(company)