If TSMC wasn't around, I think it could be argued that China would have tried to take over/invaded long before now. So if you are the government of Taiwan, helping TSMC out is in your best interest.
So are you saying that the US is actively trying to get invaded by moving TSMC out of Taiwan?
"Let's just move TSMC to the US" is a naive solution to the problem most people with little industry experience arrive at. No real effort is being made to move any significant portion of final fabrication out of Taiwan and into the US, and the latest and greatest processes are being developed exclusively in Taiwan. Progress on 5nm fabs in AZ will probably be excruciatingly slow, dependent on significant numbers of Taiwanese worker exchanges, and produce a chip 2 generations behind cutting edge by the time it's operational.
There's some backlash in Taiwan over "piercing the silicon shield", but it looks like it could end up being a way to get the US and Taiwan to cooperate even more intensely than they already do.