Replace "India or China" with "Black or Hispanic" to see how sad this comment is. It still surprises me to see that we live in a world where racism is condemned but discriminating people for the place they were born in is socially accepted.
Now, to answer your question, we should care about people in India or China because they're people. Human beings. The place they were born in, just like the color of their skin, should be an irrelevant factor. Something assigned to you randomly just before birth.
Nationalism sucks.
The irony is that people in India and China understand this simple dynamic perfectly well. You don't need to explain to the average Indian or Chinese person why they should care more for the plight of their neighbors than that of, say, even poorer people in Africa.
However, if you favor some sort of protectionism, I'm curious why you think I should care about poor Americans. Supposing I were to give up humanism and revert to tribalism, as you seem to have done, why would I allow poor Americans into my tribe? Why not simply define my tribe as wealthy white males?
(I personally have practical reasons not to do this. A minority of my friends are American and a smaller minority of the Americans are white males. But those are just practicalities, not moralities.)
I'm also curious whether you favor imperialism. After all, if our goal is simply to maximize American utility, why not just pillage and plunder everyone else?
In any case, I'm not advocating for political change overseas. I'm simply advocating against threatening people with violence for engaging in mutually agreeable trade. I.e., if I want to hire an Indian person to work as my secretary, it's not right to forbid this in order to force me to hire an American.