It never did. "Unit test" in programming has always had the meaning it does now: it's a test of a unit of code.
But "unit test" was originally used in electronics, and the meaning in electronics was a bit closer to what the author suggests. The author is being a bit fanciful (aka lying) by excluding this context and pretending that we all don't really understand what Kent Beck et. al. were talking about.
<< I call them "unit tests" but they don't match the accepted definition of unit tests very well. >>
I'm not entirely certain it's fair to accuse the author of lying; ignorance derived from limited exposure to materials outside the bubble (rather than deceit) is the more likely culprit here.
(Not helped at all by the fact that much of the TDD/XP origin story is pre-Google, and requires a different set of research patterns to track down.)
Here's what Kent Beck has to say about testing: https://stackoverflow.com/a/153565
--- start quote ---
I get paid for code that works, not for tests, so my philosophy is to test as little as possible to reach a given level of confidence
--- end quote ---