Technically... they can. It's the same authority which has allowed organizations like Microsoft to take over botnet C&C systems. The CFAA has specific carveouts to allow unauthorized access with a court order.

This is actually the new frontier in the relationship between corporations and the government. The government now allows, within certain parameters, private enforcement of public policy, if one can show damage, and the government lacks the will (or resources) for enforcement.

The theory goes, that guy is breaking the law, and it's hurting my business, but since it's low priority for the government, I'm going to start a private enforcement action. Both very ingenuous and scary at the same time.