It doesn't make it "okay", but it can make it "better" than some other thing.

And no, I'm not talking about ethnic group hiring here (primarily), I'm talking about caste-based hiring. Which would make the following a better parallel:

If a White man is only hiring White people, but is hiring from all economic and educational groups (from white trash with a third-grade education to blue-bloods with post-doctoral certifications), this is better than a Yalie hiring only other Yalies. All else held equal.

Better how? If someone who only holds 3rd grade education on paper but self taught to become a master in some field then in truth he is not holding only a 3rd grade education. But if he learned nothing beyond 3rd grade then I really hope he isn't being hired for complex skilled work that he cannot perform

Back in the day corporations used to train people to be competent at doing the job they were hired to do.

Computer disciplines are different than most others in not requiring a degree to prove competency. I'm in biology, and good luck getting any decent job without a B.S., regardless of how competent you are. For Bio jobs a third-grade education is only a third-grade education, regardless of your self-taught skills.

White trash is a derogatory racial and class-related slur used in American English to refer to poor white people, especially in the rural southern United States.

Do you have a word I can use that will get across the idea of a marginalized and looked-down-up white group in the US without using a slur?