The article is outlining very dumb arguments but it's at least a clear and lucid account of the thinking dominating the planning department, political class and many residents.
Basically, this crackpot geography/environmentalism professor is saying that supply has increased a little bit more than population growth, so that means that supply isn't the problem, that demand is. So, the appropriate policy tools are those that would kneecap demand and growth.
Putting aside how you intend to keep population growth and housing starts at their current levels if you hammer demand for housing, just think about how dumb it is to look at all these people wanting to pour money into your region and to tell them - "no, we can't, we must protect the 75% of the city made up of automobile-oriented detached low rise housing, that is the imperative. We've had enough economic growth thank you very much, now we want decline."
It's nuts. People want to make movies in Vancouver, but that's making movie equipment rentals expensive, I know, we'll tax foreign movie companies. Companies want to make software in Vancouver, but that's pushing up salaries and making it hard for local companies to compete for top talent, I know, we'll put a tax on foreign companies coming in.
Edit:
this is a good thread.