I can imagine a kid telling a parent about the fight scene with Bonzo in the shower, and (with the parent not having much context) it sounding incredibly creepy. So the parent goes to the principal and complains, and the principal (who has also never read the book) decides not to take any chances. After all, nobody wants to be the administrator who "ignored a red flag" in the case that the teacher actually is some kind of creep. So the teacher gets suspended until an investigation is complete, not because the administration is evil or stupid, but simply because the incentives are all aligned for the administration to suspend first, and then ask questions.