Poe's law in action. Given the level of response the TSA has to ridiculous scenarios, I'm almost entirely sure that a TSA agent would read this and immediately begin planning a program to defend against the very real, entirely probably threat of terrorist cojones transplants.
But would it do anything? Would the backscatter machine even see anything? What about something up the rectum. Knowing of these machines, terrorists will just find another place to stash the gear. If the backscatter machine doesn't protect against that, then what good is it, really? And, is that good sufficient for the invasion of privacy and health concerns?