There is no moral or legal connection I think, your employer is not responsible if you go into a frenzy and mow peaple down with a car 'because they pay you'.

If the US was directly involved in establishing safety procedures, then yes, that would be something.

But by and large, this is a China problem.

I doubt we will never know the answer.

If Trump had any kind of material evidence, he would have used it. Team Biden would be super strategic about it, I have no idea how they would communicate the intelligence. They would be wary of the populist consequences.

In a weird way, it might be better if we never found out that was true.