I truly don't doubt it's possible for the AI to be 'racist'.
>If the AI had recommended Black and Asian candidates at the same rate as it recommended the most-favored group (typically white applicants), 40,000 more of their applications would have advanced to the next stage of hiring.
I don't think this is the right benchmark here, or at least, it would be very interesting if the actual outcome, offer or rejected, was considered at the end.
You are misreading this sentence. This sentence is saying: "Using a constructed dataset of resumes, whose only difference was a name change, we would anticipate a system evaluating on qualifications to produce an equal distribution of candidates across names. Our observed result was highly unequal, and that warrants further investigation."