No it isn’t, in fact private companies are encouraged (and in some cases required) to have an affirmative action policy in place.
The thing you think affirmative action means “hiring less qualified employees because of their race” is illegal. You can’t base your hiring decision on someone’s protected characteristics but you are totally free to base other things on that.
Here are some anti-* takes that are totally legal.
* Someone you’re interviewing is Latino that has only worked on small projects or small features and when asked about it they expressed that they always asked to be given bigger projects but was always turned down. You get the feeling that this was likely due to his race and so you don’t hold it against him.
* You’re interviewing a trans woman who recently quit her job while not having anything lined up. She describes the last few months as suddenly having her workload increase, her code reviews getting more critical, and her pto being denied that never had before. By your estimation it seems like she was quiet fired because of her gender alignment and so you don’t consider it a red flag.
* You have the unfortunate task of needing to drastically cut payroll expenses and finance says it will be around 20% of the workforce. You talk to your senior staff and managers to recommend low performing candidates and collect metrics like cards worked and performance reviews. You’re reviewing a woman selected for termination and notice that she seems to be closing more cards than some of her male teammates which is odd, and when you dig into the PRs they’re fine, she’s seemingly not taking on easier work, and from the comments her teammates seem to love her. So you ask the manager’s manager and find out that she’s very much a girls
girl and usually passes on the “boyish” team building activities that always get voted on like doing a work fantasy league and fishing. You think it’s pretty clear what’s going on and pick someone else from that team.