Academy whores are de facto peace mongers. They pour huge resources into their training, and thus very little into units or military infrastructure. What do rulers look at before starting a war? "How strong is our army and what are our capacities?". It doesn't matter if there isn't a huge number of people doing it, the resources training suck up has great impact regardless.
That is their choice, instead of seeking game mechanics to punish them, use the existing tools to rally the realm against them and prevent them from doing so. If you can't convince the realm to act, then its simply not a problem the realm cares about enough.
