Please elaborate...
It meets the "disparate impact" criterion, which is the legal bar for racism.
Do rich golf-playing Harvard graduates really apply for a remote 100k per-year positions at Canonical? Or what is the idea of such interview?
You have identified a very specific type of economic class, which has nothing to do with "race" and/or ethnicity. I also doubt Canonical is only seeking people who "summer" in Martha's Vineyard, regardless of their skin color.
The op asserted classist == racist in the US. Something I requested elaboration on, and has yet to be offered.
In the U.S. class, income, and race are correlated for various historical reasons. Obviously "correlated" means "on average", not a rigid relationship. But discriminating based on class is very likely based on correlation to produce a disparate impact based on race.
How disparate, and how bad that is and even I suppose whether it's bad, are hotly contested ideological questions.