I think that's fine. The whole point of getting TSMC to start manufacturing in the US was to ensure that Taiwan wasn't the only place making the chips the world is using considering China has been actively threatening to take Taiwan back for decades. If TSMC can be sustainable in the US and other countries, even if Taiwan falls off the map, the technology is not China's alone. If I were TSMC, I would be trying to build plants in Australia and in Europe and South America to diversify and secure preservation should worse come to worst.
TSMC doesn't care about preserving anything. The chips being made in Taiwan is their ace card in getting western support. If they ever started making cutting edge fabs elsewhere then their importance to the west would fizzle.
There's some truth to that, but realistically speaking I think the window of opportunity on that has closed now. The US has lost every one of their own war games against China in South China Sea. So, if China decided to take military action there's little the US can do short of starting a nuclear war.