Actually TSA has beeing doing this with medical devices such as insulin pumps for quite some time. The policy change was initiated as the result of concerns raised by advocates and the same thing applies to service dogs.

It's not dumb at all and functions very well. Rather than having the swab touch the medical device or service animal, the swab only touches your hands. The experts agree that if there were any explosives attached to the device/animal, the handler's hands would show trace amounts.