Wow this administration is f**ing batshit insane. I thought the tariffs would be on raw metals, not anything at all that happens to contain them.
There's really no reason why we shouldn't have steel mills aside from that.
What's more likely, as I stated in another comment, is if you destroy their comparative advantage at a tariffed industry, the Chinese guy that had the steel mill as his best option now has to move to the next even shittier one. Tariffs are usually economically worse than zero-sum.
To answer the broader question, if you believe in markets at all, then demand creates supply, and supply for cheap (and therefore abused) labor is arguably at least in part responsible for economies like China being so shitty to your average worker. If all Western countries would e.g. slap tariffs on goods imported from places with poor labor rights, but they were specifically contingent on that (and not just a list of countries that our Great Leader has a problem with), that would put the pressure on the Chinese government to raise the standards to remain competitive. That would be the kind of tariff I would support, and I don't buy the argument that if we don't allow for such shitty jobs, the alternatives would be even worse - this is exactly the kind of attitude that creates a global race to the bottom that is the major driver for enshittification all around.
It is consistently frustrating to me to read so many analyses mentioning "comparative advantage" when what they mean is "minute labor protections compared to American standards". Americans can't freely compete when others who sell labor and goods in their marketplaces don't have to follow any of the same rules.
1) We will tariff the Chinese to make it unprofitable to sell to America anything built using anything other than our self-imposed regulations.
2) When more American steel plants etc are built, assuming investors even believe the tariffs will exist through enough administration to make it profitable, they magically will somehow be safer than working in the other industries these workers were pulled from, and magically not continue to be one of the more dangerous occupations in the USA that for mysterious reasons we want more people risking their hides in.
Reality:
1) Chinese do the same thing as always, and sell to the other 95% of the world, with no labor condition changes for the chinese.
2) More Americans get their arms turned into molten lava instead of Chinese (see recent Clairton plant explosion, yay for building more of that?). So labor conditions degrade for Americans.
3) Other Chinese figure out how to game the system enough to pretend they've followed the same rules, because lets be real, "the king is far away and the mountains are large."
4) The few Chinese not manufacturing for the other 95% of earth and haven't figured out how to game the system, are fired and work at the next even shittier job they passed on the way to the steel mill.