Think of a pediatrician, studying the symptoms and stages of a skin disease. I'm afraid the TSA would argue the same reasoning, that the pictures were necessary in a professional capacity and were not for sexual gratification. A pediatrician could theoretically be a pedophile too, but you'd need to show that the pictures were for that purpose and not a professional one, and unfortunately I think the TSA as an organization could defend itself on those grounds. If an individual TSA employee is ever found with an unauthorized cache of nudoscope images, on the other hand... And TSA missed doing a thorough background check or didn't respond to warning signs...