They made inquiries with law enforcement agencies and no one took responsibility. The rather optimistic guess in the article is that the cops were acting on their own, which makes the use of the jammer illegal.

Krugman is an economist, so he looks at the economics. When a physician looks at a patient, you probably would not be satisfied if they just said: “The patient is simply very old.” Even if that is objectively correct.

Most importantly, such a big picture answer doesn’t suggest any solution.