Not only are they apparently lying to US News, they appear to be running a scheme of enrolling an unusually high amount of transfer students (who are not counted in the US News graduation rates) for the purpose of soaking them for tuition revenue.
Per the article, transfers get much less financial aid than non-transfers at Columbia and also have much lower graduation rates, which is the opposite of what is seen at other schools with large transfer populations like in the UC system.
Prof. Thaddeus is very courageous for bringing these facts to light, and/or has a deep love for his university that he feels is being corrupted by their pursuit of a higher ranking.