The author used Vox as an example of an organization trying to tell you what to think (that is their mission statement, to explain the news) and Reuters as the most unbiased on his rating scale. You can see where the various media sources fall. Coming up right behind Vox is The Atlantic, with CNN, Washington Post, and the NYT following up behind.
Surprisingly, MSNBC and the New York Post both leaned towards Reuters on a low fiat news index bias. Hopefully, people will use this data when evaluating their sources when they realize how often they try to convince you what to think.