Predates the attack
http://www.bbc.com/news/blogs-trending-38156985
But your point is somewhat taken.
Ha, I take your point...
somewhat.
Why is the MSM (Misleading News Media! lol) suddenly so concerned with "fake news"? Because of bullets hitting some shithole pizzeria? That's an excuse, not a reason. What is the solution offered in unison? Censorship. It's about reestablishing gatekeeper status, because no shots were ever fired because of MSM publications. Except for in Iraq, Libya, Syria, Dallas, Des Moines, Baton Rouge....
This is compelling, and I think the internal contradictions here are worth looking at - i.e. that what we're calling "misleading news" is reporting (apparently) misleading stories about actual "fake news" ("actual fake" jesus fucking christ). I also think you're right that the act of violence is an excuse, not a reason. The primary reason is catering to a specific political agenda.
I'm still not sure we can qualify misleading news as more dangerous than fake news simply because it circulates more widely. As Adams suggested, fake news can have good intentions; and if this is true, then so can misleading news. My point would be that misleading news, even if it potentially has negative consequences, is ultimately positive because it contributes to a field of communication in which (or through which) different actors can express their agreements or disagreements about a subject.
One of the reasons why it is sometimes so difficult to speak across political gulfs is because of the kind of information people accept as probable, and the kinds of media that deliver such information. When Trump supporters talk about dishonest media (what we're calling the misleading news), they alleviate themselves of having to talk about topics that the dishonest media covers. For what it's worth, the left does the same thing when it talks about America's gun culture or systemic racism. I happen to accept the argument for systemic racism, but that's not because of stories I watch on MSNBC.
One project that's on my back burner right now is a paper on the current political conflict (there are many, but I mean the one that has divided supporters between Clinton and Trump) as a problem of communications, as Niklas Luhmann writes about it: more specifically, a problem between levels of meaning. This isn't to say that one group's understanding is better than another's, but that their internal vocabularies operate according to different scales of meaning. Ultimately, both run into contradictions, and both remain unable to translate themselves into the vernacular of their opponent. Luhmann doesn't really have any useful answers, unfortunately. It's just a helpful perspective on the problem; and actually, Luhmann wouldn't see it as a problem. In other words, he wouldn't insist that one side is right and the other wrong. He would say that the two sides are aspects of a distinction occurring at a higher, mostly unnoticed, level of society.