Perhaps it was Poe's Law-- The "For the children!" angle was meant with the greatest possible irony that can be mustered by a mere mortal.
Considering that the press is the major offender of 'for the children!' dreck, (because of how inflammatory it is, and thus how well it sells), that the press put that BELOW both "international intrigue, AND "So uhm, you know women have a harder time being elected, right?" in things it thinks would get readers upset about (and thus sell eyeballs), it speaks fucking volumes about how out of control the identity politics angle is.
Rather than see the interaction between Warren and Sanders as what it truly was*, they want to paint it in the most sensational way possible, and amp it waaaaay up in the pipeline, trumping even TRUMP and "For the children."
* Sanders is a known pragmatist. He and Warren have more in common ideologically than they have differences of opinion. Sanders correctly points out that their movement (against the mainstream status quo of the establishment in government) is having great difficulty gaining and keeping traction, and that any stumbling block to it could result in failure of the movement-- This includes trying a hail-mary female presidential bid (because women are harder to elect than men, QED. Point out a single female US president.). Warren disagrees-- Says that a female winning the office will send a powerful message. Both agree that if either of them win, it's a win for their movement. Go on about their lives for 2 years. It's not "Sanders SEXIST!". It is "Sanders points out sexism in politics-- Worried that betting on female candidate can doom movement." Sanders did not try to dissuade Warren from running; ergo, he is not the one being sexist. His concern is principally for the success of the movement he and Warren are pushing. The sexism he is rightly pointing out, is that of the electorate, which he has no control over, and is pointing out exists and needs to be considered, despite the chilling effects that has. Warren asserts that the chilling effect is too great an ethical concession to concede to, and feels that it needs to stop, and is part and parcel with the movement. Such is the disagreement.
But that's much less salacious than "Sanders SEXIST!"