You would be correct.

Based on the info in this post, I'm certain she was not secondarily screened because of her size but rather because she alarmed the metal detector. The skirt wanding is called the "step-forward method" and it is the method used to screen the legs when wearing a garment like a skirt, kilt, or robe. Regrettably, the screener apparently poked her in the crotch. While clearly wrong, sometimes "bumpage" happens; we can't tell where the crotch is so we have to guess. I would have apologized for that the same as I have apologized for accidentally bumping any other part of the body. As far as poking her in the fat rolls, I doubt that would be done deliberately since contact with the wand will cause the wand to alarm. However, proper wanding technique means keeping the wand close to the body and that can be a tough task with curvaceous women. Lastly, the young woman's ease in traversing the checkpoint had nothing to do with her slimness; it had to do with her not alarming the metal detector. This is my take on this occurrence.