US sanction law seems to be really scary. Everyone is scared of it.
I used to work at a company where the sanction was around something mundane like Excel or something, and we had to make it an urgent priority to ban all users from Russia to access ... spinning the wheel ... our spreadsheet functionality.
My co-workers and I found it funny that US decided to ban Russia from using an online Excel-like functionality.
* Megaspeed was evading US sanctions against China
* Megaspeed CEO was a Chinese state agent
* Huang was sleeping with Megaspeed CEO
Therefore, one of the following must be true:
(1) [Unlikely] Huang knowingly supported the evasion of sanctions. If so, he should be fired for breaking the law.
(2) Huang was tricked. If so, his judgement is now suspect.
Huang's argument is (2). In this case, the evalaution of his judgement is:
(A) Is this a one-off mistake? If so, he should be retained - he's human.
(B) Is this a pattern? If so, he should be fired - he's an ongoing risk (e.g., via regulatory action).
Huang resigned because the second affair indicated (B) - he's an ongoing risk.
As a result, the question of "who knew what when" is actually beside the point. Retaining Huang risks ongoing, overwhelming government action for evading sanctions - and the board members want 0 personal liability in that investigation.