Pretty sure this was outted as a troll by the signmakers at an lefty event.
Will dig up sauce.
Mike Cernovich Stole My Photo, Lied About It On Twitter, And Sold Trump Jr. On Yet Another Fake Conspiracy
A right-wing conspiracy theory was born at Columbia University last night, based on a lie that spread with remarkable speed from a student-led college protest to the immediate family of the president of the United States. As a result, Donald Trump Jr., along with countless others, now believe that Twitter is running interference for pro-pedophile antifascist student protesters.
https://gothamist.com/2017/10/31/mike_cernovich_stole_my_photo_lied.php#photo-1