I disagree with that conclusion: even if the chainmail were indeed very uncommon (no idea), getting it from China was so easy that he even got it when actively trying to avoid it. And since the chainmail is the revolutionary part of the idea (and the most expensive part) it might as well be the product.

He set out to get "100% made in the USA", settled for "no part made in China", and couldn't even get that. That definitely feels like a failure of the US manufacturing industry.