Besides the fact that the AZ plant does not produce TSMC's bleeding edge process (3nm) but the older 4nm, the product from that fab can't be delivered directly to a customer. Every wafer at that plant has to be shipped back to Taiwan for packaging and can only then be delivered to a customer.
So a blanket tariff would definitely apply even to the production of that plant. Which is why lots of CEO's (including Tim Cook) are trying to suck-up to Trump right now, to get an exception made for their imports.
Packaging is not trivial. I don't think either of those companies has been near the frontier for packaging in ... more than a decade? Two decades? This would be something where it would take a lot of time and throwing away badly packaged wafers to create the experience necessary. TSMC is probably better off doing it themselves in a new build versus working with partners who are so far from their level.
So a blanket tariff would definitely apply even to the production of that plant. Which is why lots of CEO's (including Tim Cook) are trying to suck-up to Trump right now, to get an exception made for their imports.