IQ tests are also distinct skills but IQ scores are the most quantifiable and studied numbers in all of psychology and correlate with all kinds of things like job performance.

I think the purpose of the interview is the same thing. Even though there's no strong evidence for a correlation it's reasonable to believe intuitively that there is.

I suspect (and have seen some evidence) that the interviews he aced were algo-based. Doing well in these is very repeatable, with low additional effort. Behavioural are much harder to do at scale.