An admissions director once told me the admissions process at highly selective schools like (Stanford, Haas, etc) is like completing a jig-saw puzzle. You hand-pick every piece (applicant) and make sure that it fits in and completes the big picture (class). You don't pick a bunch of pieces together and drop them and hope to automatically complete the picture.
I see the same happening here. They must have had a few "must-have" type profiles who they must have offered, if they accepted, then planA, if they denied, then planB type of process.
We might be reading too much into nothing here, or this might be indeed that intricate process of putting a class together.