Little public interest in the secret service pursing a 25yo megalomaniac moron, who thinks installing spyware makes him the hero against the forces of institutional evil.
I imagine apple contacted the secret service in the first place because they weren't sure what else he'd done, other than, installing spyware across NY's apple stores.
Once they realised it was just an art project, I imagine they backed off to be kind, not because he couldnt be prosecuted. He clearly violated the CFAA