Yeah keep reading. You're given one fake right and there are 100 other laws. Just because you're the right shade, telling a cop to F off, is a crime in itself even if they're completely wrong. Most people would be arrested just for that.
And that is the entire point. If "the law" is completely discretionary based on the encounter you have with the enforcers and the punishers (police, DA, judges, etc), then you have no rights. Step out of line and you're in prison.
The US is a shithole.
If "ignorance isn't an excuse" doesn't get you out of any law you break, it also doesn't get you out of accidentally joining a terrorist organization due to propaganda.
Because that's exactly what it is.
It is no different than the teenagers that join ISIS. Propaganda takes them in, they join voluntarily, they live with their consequences for life.