Some helpful observations from E.S.:
"I would like to point out that with respect to the TSA (or anyone) wearing gloves, the gloves are meant only as a barrier to the wearer. The article you linked says the TSA wears latex, but given the prevalence of allergy to latex and the pictures I've seen, I think they are wearing nitrile. The type of nitrile gloves used by the TSA are relatively porous (more than latex), especially after being worn more than 15 minutes or so. The gloves are never sterile to start with, so the TSA keeping them in their pockets doesn't really affect passengers. However, the gloves should at the very least be changed between each search. Can you imagine if a passenger has lice or crabs and the TSA does the waistband check, then moves right on to the next passenger? What if someone has MRSA?"
"I work in a laboratory where I routinely test all manner of bodily fluids for infectious agents and I occasionally draw blood intravenously. I use the same kind of gloves. They are not marketed as anything but a basic barrier for the wearer, not to keep patients clean from the wearer's germs. Had I been subjected to a search, I definitely would have insisted that the TSA wear new gloves, and that they change them in front of me. There is also a proper way to remove gloves that have any chance of being soiled. Essentially, in the lab we are taught to regard all samples as highly infectious and take proper precautions to prevent the most minor of chances that there could be disease transmission. I somehow doubt the TSA are trained in these details."