A big assumption
This sort of tactic stems from the hubris in thinking that China and Chinese engineers and scientists can't figure anything out on their own. There are thousands of bright Chinese students attending US universities. Some uni's have so many that it's more likely to hear Mandarin spoken than American. It's often that the technologies of tomorrow are interesting research being done at universities today so much of the sort of advancements that China will have will come from the students of today returning home and having access to R&D funding and industry support that's evaporating in the US.
The whole "national security" agenda is pretty silly anyway. The US State department is arguing the regulation of things that are already obsolete. When I was working in aerospace, there was a huge blanket on who could be hired and how we could share information even though everything we were doing could be learned from a handful of reference books and old NASA tech releases. Our novelty was how we were putting these known things together. We weren't rocket "scientists", we were rocket "engineers" making the known into something useful. The non-technical government wonks didn't understand the difference, but they could generate page upon page of senseless verbosity that sounded impressive and preserved their jobs.