Essentially, the author admits that it is a given that protectionism harms the country. But most of this harm, he asserts, will just fall upon the 'coastal elites'. It will create jobs for the poor. Therefore we should do it. An uncharitable reader of the article might be tempted to suggest that the author therefore sees only benefits, i.e. hurting the rich ceterus paribus is a desirable goal. Means-testing people to determine whether their interests are worth protecting is not an admirable position (as perhaps implied here). However I aim not to be uncharitable, so I mention this interpretation only for your personal interest.
The argument suffers from a flaw which is endemic in anti-trade positions - incorrectly or inadequately considering the effects on countries other than one's own. The argument presupposes that it is morally acceptable to hurt the rich to help the poor, but doesn't consider that unemployed Chinese are poor on a level that reaches far beyond the most destitute of Americans. The reason protectionism would create jobs for poor Americans is because it would stop firms employing Chinese people to do the same job.
Unless you are prepared to argue that Chinese people are worth less than Americans, no-one can possibly accept the argument as presented. I would hope the author isn't prepared to do that, but unfortunately I am not too sure. I suspect (once again) that it is a case of inadequate reflective equilibrium - people have essentially xenophobic intutions which conflict with their other views, but for some reason they have not noticed this and thus have not resolved the tension in their world-views.
As an aside, to someone like me with pro free-trade views, the comments are actually a little terrifying. E.g.
We are in a trade war, and losing because of the almost religious fervor of "free trade" advocates in the Commerce and Trade departments. That's like fighting a real war with a bunch of born-again pacifists as our Generals and Admirals.
This just shows to me once again that at the level of public discourse, anti-trade argumentation is on a par intellectually with creationism.