MSFT may have offered them a lucrative offer to join (for the time being) in order to alleviate the potential stock dump.
i totally agree, except stupid-lucrative is still in the equation, like Elon Musk rich, not because of the money, but because it says "my electric cars did more to stop global warming than anything you've done"
whether this round of AI turns into AGI doesn't precisely matter, it's on the way and it's going to be big, who wouldn't want their name attached to it.