The author points out that in different words that if the school is worried about bullying, etc, then the appropriate response is to protect first, not work out who to punish first.
Trying to come up with fake guis and hiding stuff is not how this sort of issue should be approached. The issue needs to be squashed, and firmly, so that it doesn't occur in the first place. Prevention is better than cure, or in the case of a fake gui, less than half a cure.
The word "privacy" does not appear in the Constitution - you have no explicit right to privacy in the US
According to the 4th Amendment to the U.S. Constitution, the People have the right "to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures". That is an explicit legal right to privacy, even if it doesn't use the literal word "privacy" in the text.
At the end the only way to win this cat & mouse game is to stand your ground before it starts.