yeah I get what your saying lachie and it is a good point. Personally I see no harm. however as Robert B said, its the school rules that ultimately determine what your allowed to bring in. Just like if my highschool brought in a rule saying that all male students weren't allowed to wear a certain brand of clothing, then thats the rules, its sucks, but you can't disobey them really, as school rules are pretty rigid, and even if your principal/whoever the person is who enforces the rules has common sense they also can't flick it under the mat so to speak as they then have to follwo guidelines by dept of education i think.
Like for example, during some boring class, me and a mate wrote a whole page of pickup lines, the teacher saw it, sent us to the principal, and he was quite cool about it, you know laughed with us, but he had to discipline us, as it was the rules at our school.
EDIT: not trying to patronise you having finished school, its just sometimes you gotta play by the rules, sure sucks though
But I think if you really have a concern go talk to a teacher about it, or the principal him/herself and just see what they say.