In FTX's case there obviously was a crime - stealing customer money. With OpenAI I don't really see it, hence I guess the lack of a criminal case. The 'stealing a charity' bit is more metaphorical - it wasn't actually stolen, just the control kind of moving from friends of Musk to friends of Altman which was inevitable when Musk quit.

I think Musk is alleging unjust enrichment of Altman and Brockman but given they only have a small percentage in the for profit they set up it's going to be hard to prove that's unjust in court I guess.

You could argue OpenAI had drifted from its mission to be open.