The author clearly has an agenda and basically wrote the article around it. Why all the conjecture?
I was bored so I did a very crude estimate.
Houston has 982,694 homes according to the census data in 665 square miles.
Austin has 426,899 homes in 271 square miles.
So Austin is denser and more expensive. To me this makes sense. Denser areas are more popular, and popularity results in high income people coming in and biding up prices. This is why there are no dense areas that are cheap.