Much like spaceflight, aerospace or nuclear engineering, you need to retain local talent for national defense purposes. Being 70% as good is still way better than being 100% dependent and heavily leveraged by your opponents.
It gets a little weird when you start thinking of AI like that, because AI is very corporately based in the US and China, but not as heavily that when from a talent position.
Demis Hassabis and Google's Deep Mind are all British in terms of location/talent, but they certainly aren't from a coorporate perspective (Deep Mind work might happen in London, but it is owned by Google, as US company)
(I don't know a lot about nuclear/aerospace industries, I'm guessing there more location centered just in virtue of being based around physical things, but I could be wrong)
If your employees are only 70% as good, as skilled, as knowledgeable while not knowing it, then you can absolutely kill a reactor just like Chernobyl. The overconfidence is what allowed them to put the reactor in the state they did and not realize the implications.
Far worse than 70%. Chernobyl was a catastrophically flawed reactor design. Operators ran a badly planned safety test in which operators intentionally caused a dangerous state while key protections were disabled or bypassed.
