Yeah, even for Cassius, I don't get his angle here.
He doesn't understand that propaganda != history. Ask any FOX news viewer and they will say the same thing that Cassius does. "So what if its propaganda. Its history/news."
I really doubt anyone would willingly admit that the news they watch or history they believe in is propaganda. Most just prefer to say that about the news/views of other people.
I don't think the Left or the Right in America is pushing propaganda in the sense of blatantly lying. No one is telling students that Ronald Reagan was born atop a mountain while a double rainbow appeared in the sky as an auspicious sign from the Heavens or characterizing the Cold War as a vast communist conspiracy against the virtuous American people.
But there are only so many days of school and only so many pages long that history books can be. Some things inevitably have to be left out so that others can be included. There's the rub.
A week talking about Phyllis Schlafly is a week that can't be spent talking about Rachel Carson. If you spend too much time talking about the booming economy of the late '80s, you leave no time to discuss deindustrialization or the decline of inner cities. If you want to talk about Jim Crow, you have to cut World War II short. Everything has tradeoffs.