The author tries to make a point but drowns the reader in a sea of definitions and data without providing a useful navigation. After reading the article and trying to re-read some sections I noticed that he lists popularity as a criterion:

  Popularity, which correlate with:
     - number of tested libraries
     - facility to find learning material
     - ability to find another developer to work with

With those points added popularity looks like a useful metric. However, a little later

  RedMonk Programming Language Rankings (January 2013) provide an apparent
  good measure of popularity. While not perfect the current measure feel
  mostly right. They create an image using stack overflow and github data.

This is so far from perfect and almost unrelated to the points the author had just made above that I decided not to take this article seriously.