If you have a refutation of Triumph of the City, it will be groundbreaking. Until it’s published, throwing in like one credible source would make your comments more serious.
I read "Triumph of the City" about 15 years ago. It's a well-researched book, and it literally makes the same points as I do. In particular, it describes the density death spiral much better than I can. It's a bit outdated regarding the carbon footprint because it was written before the EVs and self-driving but that's a fairly minor point.
Its biggest problem is that it was written before the negatives of the density death spiral became apparent.
The cities in the early 2000-s were the main benefactors of the global crime collapse. So suddenly, Times Square in NYC transformed from a blighted area into the world's most valuable real estate. How could you be negative about urbanism seeing that? Housing in cities was also relatively cheap because cities used to be less desirable than suburbs.
If I were to summarize, "Triumph of the City" is factually correct. Just as the statement: "coal power plants are a triumph of engineering, providing cheap, reliable, and accessible power".
Edit: another important thing that he's missing is the end of the population growth. So now it's a nearly zero-sum game: a new housing unit in Manhattan means one more dilapidated house in rural Ohio.