"News diet" is a Stelterism. I don't know if he got it from them or they got it from him. Brian Stelter wants to have the same control over news that Michelle Obama had over school lunchers.
These are precursors, or a setup, for the eventual censorship of the media, in the future, under the guise of “public safety” and “good of the people”.
They will be able to say that these watchdog groups have been well established (even though it was a political setup from the beginning) and “non-partisan” and then when something comes out that’s mildly controversial, they will say “See look at their independent scoring, and now they are publishing radical information detrimental to the public good”.