> no one cares about the affairs
That's not certain. I tend to agree with you, but it is possible that the concern is for the effect on the employees. Especially the 2nd known affair is a violation of HR rules that are supposed to apply to everyone, and it's hard to argue that when you don't apply them to your CEO. By itself, I'm highly doubtful it would be enough (you can slap him on the wrist or something), but the effect on morale and company culture is a much larger concern. If people lose confidence in the company, they're more likely to jump ship, so you pay them more. And if investors lose confidence over any of this, then that's a much bigger and more expensive problem. There's a moral standard behind these types of things, even if it doesn't directly matter.
What we don't know and what really happened at the emergency board meeting are probably the key here. I'm sure there's plenty more going on that we can't see. More affairs are obviously possible, which is kind of meh until you find out who they were with and what deals they were part of.
It's even possible that Huang made the call -- it's not like he's going to escape public shaming at this point, and depending on his calculations of the repercussions, he could easily have tens of billions of dollars riding on this. He is clearly good at taking actions that maximize the market value of his company -- might this be another such action? Our armchairs aren't the best perspective from which to evaluate that.