Warren's version of what happened in that meeting had been a rumor in DC political/journalist circles for over a year, so it wasn't some out of left field shocking turn of events that it eventually made it to the front pages. CNN dropped it right before their last big debate when it could be deployed to maximum effect. Conspiracy theories about Elizabeth Warren shanking Sanders is great fodder for the gawking masses who treat elections like their favorite TV show or are desperately looking for reasons to hate Warren, but thinking about it for more than a second would indicate that it's a highly unlikely course of action for Warren to take.