I don't know about A. I realize that iPads aren't exactly known for being closed books, but the school would need to be targeting it specifically or perhaps inserting scripts into all of the students' requested webpages. Either one seems like a long shot though, unless the principal is some kind of info-voyeurist.
It seems more likely that an ad's script scanned his history and tried displaying a suitable ad, only to trip a filtering mechanism.
@Arranis Thelmos: Does your school's server have a filter installed on it?