In my own antecdotal story of flying with my 18 month old, we had a could-have-turned-ugly scenario last month.
I am pregnant so I opted for the patdown. I was also wearing DD in the Ergo because she likes to run so she had to get patted down as well. DH went through the regular screening but was 3 feet away on the other side of the magical roped off area.
I had to take DD out of the carrier so we could be patted down separately. Again, fine. They had me put her on a chair a few feet from me (closer to DH, but still on the other side of the "fence") while I got searched, which FTR, is not pleasant and a little bit gross. While I was getting patted down, there was another TSA agent watching me getting patted down, but no one was watching DD except for DH and I. She started squirming and climbing out of the chair, and I reached over to make sure she stayed on the chair. They told me I wasn't allowed to touch her because she hadn't been patted down. Uh, ok. Then make her stay on the chair.
I motioned for DH to come over (he was putting on his shoes at this point) and they said that he couldn't touch her because he was clear but she wasn't. I told them at least a dozen times, "I don't need to touch her, just make sure she stays on the chair." She likes to run around and if no one could restrain her to make sure she was not running around through security, we would have a bigger problem.
I'm watching her get out of the chair, but they aren't allowing me to put her back in the chair (no touching, remember) and DH can't put her back in the chair either. Again, I told them, just make sure she stays in the chair for her safety. Nope, can't touch this. By this point, I just walked over to her, TSA agent still grabbing at my thigh, and physically blocked her with my body so she couldn't get down. They couldn't fathom DD wouldn't just listen and stay seated. "Ma'am, you need to stay seated, " they tell my daughter. Yeah, ok, getting an 18 month old to sit in a chair while 2 adults are calling her ma'am is going to go over well. Cue the meltdown. Nope, I can't console her. She's not clear yet.
Ho.ly.shits. Finally, after an eternity, I could stand her up next to me and they patted her down. "Her diaper area felt a little thick." Yeah, it's a diaper."
By this point I wanted a cocktail at 10am.