It wasn't "scientific racism". First of all its discussion of science pertained to differences in gender, not race. And the author did not argue that women were worse at engineering, but rather that gender differences affect preferences.
While other people may have used his memo to justify sexist beliefs about the capability of female engineers, attributing those words to the original author is at best intellectually dishonest if not outright dishonest.
100% agree. Of the people I know that read the memo (incl women), I know of none who disagreed with it. It's genuinely hard to disagree as he presented facts backed by research to support a theory on the gender balance in tech.
I will add that many people who only read articles paraphrasing and quoting it, did seem to react unfavorably, likely taking the opinion the article wished to portray.
While other people may have used his memo to justify sexist beliefs about the capability of female engineers, attributing those words to the original author is at best intellectually dishonest if not outright dishonest.