The problem I find in your reasoning is that the guys texting about their "plans to detonate a bomb during the game," are planning harm whether anyone sees their texts or not.  In contrast, the texts that these two men sent each other were only damaging and incendiary BECAUSE of the photographer who made the conversation public.  The photographer hurt more people than anyone: the two administrators, the students mentioned, the parents and friends of those students, and the parents and friends of the administrators themselves.  Without the photographer, none of this would have happened.