I think you're quite mistaking nationalism for racism -- the former the most widespread basis for tribal affiliation in the world. In my case, it's more that it's a UK citizen which raises my eyebrows.
While I feel some disappointment and regret over how people of other countries might be treated by US immigration, I feel no sense of "tribal injury" as I do here. In other words, my instinct to say, "how dare a person from my country be treated this way!" is not aroused when it isnt my country.
Skin colour is irrelevant, and I'dve very much the same reaction either way. As would the vast majority of people in the UK who, if racist, are towards people from south-east asia not south america (races for which we have no real experience).
It is quite common that people from one nation take issue with their nationals being mistreated --- the reason this is on the front page of HN is that it's an english-speaking country (this is an english site), a european one with some common cultural affiliation, and a reasonably powerful one (one whose voice on the matter has an outsized impact vs. population size, sauy).