What about tucking the front ends of a bandana up into his helmet vents, or attaching it to his helmet some other way, so that he can just slap it on in transition?
One of my riding buddies doesn't have his head shaved all the way, but it's a very short buzz cut. I'm not sure what kind of a do-rag it is that he wears, but he doesn't have any trouble re-tying it himself. But yeah, it does take him a few seconds, more than someone would want to spend in transition I think.
This just occurred to me - what about taking one of those microfiber kitchen cloths and cutting a strip (maybe doubled over) to attach to the forehead of his helmet? Those things are super absorbent, and by cutting a strip, he wouldn't be blocking the vents.
Speed comes from what you put behind you. - Judi Ketteler