The crime here isn't giving secrets to the Chinese, it is helping them evade export controls. Again, this is something that Nvidia and Jensen has been investigated on repeatedly. If he knew that Megaspeed was a front for China, quite hard to deny given that Alice Huang seems to have brought Chinese execs to every meeting with Jensen then it is very bad. And yes, the stuff that Jensen would have said would have been very useful because, I assume, the inference is that he would have been helping them evade sanctions.
The very best case from here is that the board fires him.