Law in the US tends to come only after abuses have happened, especially with regards to government powers. It was a brilliant marketing strategy on the part of the companies providing the cell tower simulators to claim they were covered under "national security rules" to avoid giving secrets to terrorists -- even though use of such cell site simulators by police/military has been commonplace across the world since the 90s. Especially in the types of totalitarian regimes that often push people into extreme ideologies. It prevented this from being much of a story for a long time, and by shielding the source of information in court, it allowed them to sell a lot of these devices before the legal system caught up.