Since many people (myself included) have a genioplasty done in addition to other work, they probably have very few cases of JUST genioplasty. So maybe they're including everybody who's had a genioplasty regardless of whether it's in addition to another procedure. Maybe check to see if they're also included in other sections?
Although on second thought, there are only three examples, maybe it is just a genioplasty?
Third thought - I checked the orthognathic section, and the older woman is included in that section as well as the genioplasty one.