….but they only got it because it was assumed that they would operate as impartial, open channels of communication—not curators of acceptable opinion.”
All that they did was echo the amended Holmes opinion which defined banned speech as emboldened below. They had every right to throw that treasonous, riot inciting, prick off their platforms
"Shouting fire in a crowded theater" is a popular analogy for speech or actions made for the principal purpose of creating panic.
The phrase is a paraphrasing of Justice Oliver Wendell Holmes, Jr.'s opinion in the United States Supreme Court case Schenck v. United States in 1919, which held that the defendant's speech in opposition to the draft during World War I was not protected free speech under the First Amendment of the United States Constitution.
The case was later partially overturned by Brandenburg v. Ohio in 1969, which limited the scope of banned speech to that which would be directed to and likely to incite imminent lawless action (e.g. a riot).[1]