In some ways, this does seem like a good idea. On the surface atleast.

But the problem does arise, where is the line drawn? What, exactly, is a niusance?

The law allows you to go in without permission and abate, or stop, the nuisance. *You can even sue the malefactor for the expense of the abatement*.
This, especially, raises the alarm. It seems sort of like someone breaking into your house, stealing you blind, cutting themselves on purpose before they leave with your stuff, and suing you for $100,000. (It's happened, and been awarded.)

I can just see it now. Some kid hacks some medium sized company, and sues them, claiming they hacked him first.

Do we REALLY need to make Cracker Wars legal, and add in an incentive like this?