I can't speak for the OP, but it's not like there's actual separation between the sense of morality an individual uses to make decisions about sex and relationship and the sense of morality an individual uses to make commercial decisions. It's the same person with the same set of values making choices in two separate domains. It's not two different people.

This will be particularly evident if the GPUs to China aspect turns out to be true in addition to the affair. It's not really a surprise that someone who might view themselves above the vows they took to their life partner might also view themselves above their other legal and moral obligations. (Like, in this case, following export laws.)

Beyond all that, it's also not unreasonable to expect our leaders to lead by example. The affair with the spy was setting a bad example. The affair with a subordinate was setting a bad example. You're right that a part of that's about sex, but it's equally much about personal judgement, risk exposure, what it means to lead, and the organization you aim to create. So I wouldn't be so quick to diminish it as being solely about "other peoples sex life".

(Yes, I get that I don't know if they had an open marriage or similar. Even if they did, there's still a lot of this that's reprehensible. And we don't know they did.)