You don't know that it's illegal to enter a classroom without permission? Even if you really, really think people need to give you time & attention & listen to you, this doesn't mean you have the right to make them via stalking & turning up at their work.
Show that he has ever said that people should welcome stalkers into the same room as them? Is there never any reason I could call the police on someone coming to place of work? Even if I've told him to leave me alone, blocked him, got restraining order?