The reason why is obvious - they're interacting with real spooks. How 007 is that? What could be cooler? And the real spooks said all sorts of stuff about how the meaning of the warrant is terribly complex, technical, not at all scary and absolutely essential to national security.
Oh, and accidentally destroying civil liberties is less of an electoral liability than accidentally allowing an unsuccessful terrorist plot to get further than it might otherwise do, so the safe thing to do (from an electoral liability point of view) is to sign everything put in front of you.