pretty long rant of an article. He seems to be criticizing most vertical jump programs, rather than the concerted effort to improve a vertical leap. He also defines the vertical leap as a standing vertical leap.
Let's not overcomplicate things. If you want to dunk, train to jump higher, once you're there, practice the skills necessary to make dunks look beautiful. If you improve your running vertical jump off of one leg, or two legs, you will be more likely to throw down a powerful dunk.
I do agree though that standing vertical jump training may not be necessary to improve your ability to dunk off of two feet in a game, and the two aren't always related. Many times they're not.