The didn't tell CNN "We're going to go shoot a school up and need you to come film the coverup". CNN got pimped as a useful idiot. They dropped programmed, trained kids into their lap. CNN producers responded like the pavlovian dogs they are.
Once the handful of CNN who understand the big game realized what happened they were so deep into the shit they faced an existential threat. Double down on the bullshit or cease to exist if exposed.
Same way they exercise control over people with pedo blackmail.