Classifying government documents is not censorship, since it's not government suppressing anyone's speech. It's strictly a transparency issue.
All of your other examples involve private censorship (which can be rephrased as "people and companies exercising their property rights and freedom of association"), not government censorship.
If you know about it, it's a felony to talk about it. That particular one was a huge omission that might have shifted national debate in a different direction, esp who U.S. would target in a war or sanction. I still remember the advertisements on the radio talking about how great Saudi Arabia is and how good buddies we are. Be a different picture if U.S. media said they were a huge sponsor of violent religion and terrorism with that part of 9/11 report highlighted for all to see.
Definitely an example of mandated censorship, corruption, and maybe some kind of conspiracy. Maybe protecting politicians' and Saudi's interests at everyone else's expense. Even if it kills a bunch of us. If that's how they use the power, they don't deserve to have it.
All of your other examples involve private censorship (which can be rephrased as "people and companies exercising their property rights and freedom of association"), not government censorship.