You don't know the steady state is harm to poor Americans. That Americans are poor is likely a consequence of the current trade imbalances.
This story is improbable because the overwhelming majority of America's poorest are employed in the domestic service industry who are not facing negative exposure to international trade. Every store clerk, every McDonalds worker, every garbage man, cleaning lady, janitor, nanny, teacher and so on will be one-sided losers of an increase in prices due to reduced trade.
The benefactors will be a relatively small number of American manufacturing workers (given that it's overall only a small source of employment), who already earn solidly middle-class wages.