Re: It's not the building or the hardware ..
The people aren't a major part of the cost of a chip fab and the skilled people you need to run one aren't that much cheaper in Shenzhen than in Toadsuck Arkansas.
The products will still be made in china because that is labour intensive, it's just that the chips will be shipped from USA rather than Taiwan.
For TMSC this is a great move, they get a fab built for free - assuming their tax accountants are any good. They get a captive market with infinitely deep pockets - US military/govt/etc required to buy made in america "Freedom chips" from TMSC at whatever premium they want to charge
Any threat/boycot/law suit aimed at TMSC from anybody in the world becomes a threat to America.