If he's white, as he says, and at least in my experience, nobody is trying to figure out our "race." It's "white" lol, nobody questions it. That and white to white nobody is ashamed to straight up say "what is your ancestry" because no white people (except maybe OP) get offended by it, they always just answer "mostly Irish with a bit of English" or "German, French, English" or "Serbian" or whatever, especially in a "melting pot" country like the US or CAN, so if they wanted to know they'd just ask, between white people that question (regarding ethnic background/ancestry) is as innocuous as "what'd you have for breakfast."

I'm betting he has an accent, and they were asking where he was from but he gave an obviously cold/strange answer, and they didn't know where to go from there. They should have just realized that OP was sort of hostile and doesn't want to talk, and ended it there, yes, but they probably weren't trying to be "racist" to someone who ostensibly is just "a white guy who says aboot, eh."

Idk where you're from, but in America the only people alive when that type of racism was prevalent are ~100yr old. Maybe some old WWII vets still hate the Italians, but mostly, even in my conservative southern location, nobody cares who the "real whites" are. I've even met and argued with actual racists who actually hate POCs and even they still accept all forms of "white," even "white hispanic or latinos."