My response would be this:
Look, defending yourself is not the wrong thing to do. Defending yourself with unnecessary violence would be wrong. Most schools will talk a big story about "zero-tolerance", but IME tolerate bullies and punish those who defend themselves.
Using Aikido to defend yourself without a violent response puts the school administrators in the position where the have no choice but to apply consequences to the bullies and are hard-pressed to justify punishment of the person defending themselves. This, IMO, is absolutely the Right Thing To Do.