Wouldn't it be better to address the article on its own merits, whatever those may be, instead of looking for the author trying to make an ad hominem argument?
Personally I think raising taxes on second homes, rentals, etc would free up a lot of housing to purchase. Do we want to do that? Are people happy renting and not buying? I'm not sure.
You are mixing landowner profits and developer profits. Developers want low prices for new land in greenfield areas that will make the resulting houses appealing. Landowners want high prices but they also want to actually be able to sell - it doesn't matter how much your land is theoretically worth if nobody wants to buy it because they can't build on it.