In my twenties, my husband spent months going on endlessly about his new best friend "John." John this. John that. It aggravated the hell out of me. He gushed about the guy.
Then one day hubby and John arranged for the two families to meet and it turned out John and his family were black. The surprise showed on my face, which made for a very awkward meeting.
I didn't care that they were black, but my husband had never once mentioned that John was black. So I assumed he was white.
In that moment, I realized this was a racist assumption. This assumption that if he isn't white, my husband will inform me of this fact, was an artifact of a deeply racist culture. And I was tremendously upset to realize I had drunk the koolaid when I thought of myself as an idealist and not racist and so forth.
So I am very uncomfortable with the possibility that I may yet still be obliviously doing things that help keep racism alive, help keep people of color oppressed, help keep doors shut in their face without being aware of it. I don't know the solution to that and I think if you really truly believe in justice and equality, that should bother you. If it doesn't, then you are probably part of the problem and just not really wanting to take responsibility for that fact.
But, yes, nitpicking about a single word (or a couple of words, in this case) is often a cheap way to lord it over people and act morally superior without really doing anything of significance. That much, I agree with.
How can an assumption be racist anyway? If my friend told me about a friend I might imagine that person tall and slim with brown hair and whatever other look and if this person turns out to be short and chubby with blond hair - who cares. Obsessing about skin color like you are doing right now is completely meaningless, doesn't help anybody and just feeds the segregation even more. You can't be "subconsciously racist", don't believe those hoax psychologists that claim it.
The assumption was rooted in cultural practices of the Deep South.
Studies show that people who disagree with primary racism will still agree with secondary and tertiary rules that help enforce it. So you may not like the idea of subconscious bias, but it's quite real.
It is sort of a social "Jim Crow" law. Like when people say they aren't racist, but they wouldn't hire anyone who "sounds" black (who has the so called black accent) because you need to be articulate for the job. My rebuttal to that back in the day was "George W. Bush." Because if you actually need to be articulate, then a white man widely mocked for his speech issues should have never been president. But that's not really it.
Very easily: "you're Irish, I just assumed that you were a drunk".