It's a great point, and yes, things are not quite as cut and dry as I put it. State propaganda is the exact case I can think of where things become more grey. But also where rebellion becomes more tricky for teachers. I for example, if I were teaching at a public school in the US, would refuse to do the pledge of allegiance with my class. Swearing loyalty to the State is a deeply disturbing idea to me. That's not patriotism, as it is often framed, but is servitude and is the strongest form of propaganda.

I also would veer from the established nationalistic narratives in history class. So yeah... being required to incorporate any national security law in my classes... That would be a big nope from me. But I wouldn't expect to last long at a public school. Schools don't allow open defiance for long. Someone who is able to play the game and rebel in more subtle ways would have much more success than I would.