Partially correct. Though elderly people are not singled out for extra screening, it is more common with them. You are partially correct in your assertion that it is due to the infrequency of travel, infrequency not resulting in SSSS, but more from the lack of understanding what will set off the metal detector. Also, they are more likely to have metal implants that set off the metal detector. They may have more medical issues that make it hard for them to remove their shoes, or have a pace maker; thus resulting in extra screening. Lastly, a lot of them don't keep their I.D's current, also resulting in additional screening.