"Oh who cares who he slept with, he's been great for Nvidia. Nothing has been proven."
He's one of the most visible CEO's in the most visible industry in the world, and the entire AI economy is dependent upon them. The perception of him as stable is incredibly important.
Merely the suggestion that he is having affairs with people with close ties to China's government, given export controls, is a huge PR problem. Adding in an additional affair with someone under him. And the likelihood that there may be even more out there.
I doubt the Board wants to get rid of Jensen Huang. He's done incredibly well for them. But right now, there's a huge PR shitstorm swirling around the company.
Maybe in six months it all dies down and he comes back, who knows. But right now, you really can't just ignore the problem and hope the media doesn't care about the whole "well she was only sort of a spy" situation.