One of the problems is that the article ascribes a lot of decisions to the editor that were actually made by the writer or the director. Which is weird, because something can't be an editing decision if it had to be shot a certain way, because editing comes all the way at the end after everything's been shot.

Of course, writing about film is hard, because it's such a collaborative medium. It's hard to attribute a decision to a single person, when in actuality it was probably hinted at in the script, then improved from the director talking to the actor, or the DP suggesting an experimental camera angle, or the editor finding an accidental shot that just happens to work for the scene.

So let's look at whether some of these decisions were born in "writer," "director", or "editor" land. I'll pretend that Whiplash wasn't written and directed by the same guy.

  However, after rushing to get to the studio, he 
  realizes that he is early — by 3 hours. He was 
  manipulated, leading him, and us, to question: 
  should he trust Fletcher’s version of “time?”

This series of cause-and-effect events is the story, which is the purview of the writer.

  Andrew re-enters the rehearsal space in slow-motion.
  He gets behind the drums, also shot in slow-motion,
  until Fletcher re-enters the room, which resets the
  film into normal motion. 

Again, if you had to shoot it in slomo, it wasn't the editor's decision. It's hard to say if this would come from writing or directing. The script could say "he approaches the bench in slow motion," or it could say "he approaches the bench" and the director intuits that the film should ratchet up the tension.

  It’s interesting to note that while his drumming is off, 
  the editor chooses to place cuts of Andrew placing 
  band-aids on his hand that are in perfect rhythm with 
  the timing of the ride cymbal –-

This does sound like an editing decision. But again, the script could easily say "He band-aids his hand in rhythm with the cymbals."

If you want to read more about some actual decisions an editor goes through, I highly recomment In The Blink Of An Eye, written by sound and film editor Walter Murch. Tony Zhou's Vimeo series Every Frame A Painting is great too, although it focuses more on directing and cinematography.