You left out a couple of rather damning facts about CNN’s behavior:
First, CNN’s statement stated that the Redditor told them that if his identity were revealed, it would put him in physical danger, and CNN acknowledge it as fact. And, yet, they still threatened to reveal his identity. Requiring something from someone (an apology and promise of never criticizing CNN again) under threat of violence is, by definition, criminal blackmail.
Second, it turns out CNN actual fingered the wrong troll. The video tweeted by Trump is slightly different than the one posted by the Redditor. So they are blackmailing the wrong person.