Is it a crime to train people how to hack ?

Forget state law. Unless your students are law enforcement authorities or maybe telecom officials, what you propose is nothing short of wire fraud, a federal offense that also attracts civil forfeiture. This is the sort of course one would expect cops to give to one another. Proposing such a thing for the general public's consumption would probably attract the attention of law enforcement - that is, in the unlikely event it passes muster with the outfit intending to sponsor or host it. But why test those procedures? Why not float your proposal with the California Attorney's Office? I'm sure they'd be glad to hear all you know on the subject!