There are a lot of good reasons to buy American made. And a lot of good reasons not buy Chinese (mainland Chine) products. However, the Broken Window theory in the third paragraph is flawed.
Any money saved buying a less expensive product is then available to be spent buying other products and services. If I could find an American made toaster (presumably more expensive) then I would have less money to buy bacon (American grown and processed) to go with my toast. Then the American farmer loses out to save the American toaster makers. (That is assuming you can find an American made toaster. Our 50 yo Mary Proctor toaster died last year and none that I could find were made in the US.)
Let's take his T-shirt example. I go buy 7 t-shirts and spend $35 more buying American made than foreign made, then it's $35 less to spend on other things. So I'll stay home and have toast and peanut butter instead of going out to eat. The local restaurant and their workers have less business and less income, and possibly go out of business. The money thing balances out one way or another.
Don't get me wrong, I'm all for buying American made and supporting local farmers/ranchers/industries, especially the micro-brewers
, but the macro-economics of it isn't the reason why.