Well, unless that person had long hair or face piercings or their pants were too baggy, all things I’ve watched my right-wing bosses in my life explain when it came to why they didn’t hire someone I would have hired at various times. Everybody has biases. I agree that many left-wingers have used political or social opinions like this as a basis for their biases for quite some time now. But I promise we don’t have a monopoly on being ****ty hirers, or that we have an oversized share of highly comped professionals making all the hiring decisions.
I do think some of your own sentiments might help explain why certain fields seem to be more left-leaning. Fields like psychology or philosophy tend to ask questions that I’ve found most intelligent conservatives I’ve encountered don’t care to question as much. I think part of it as the relationship between political opinions and religious opinions, another is current cultural attitudes toward these types of fields, and yet another is the relative financial situations of the average bachelors-level graduate of these programs.