I'm a little tickled by the author's clear concern about the idea of giving coffee to a child, yet in our society we give adderall - amphetamines - to preschool aged children. Caffeine really seems pretty tame in comparison.
We give amphetamines to children only with the consent and supervision of a doctor. Whether or not it's a good idea, it's certainly a more controlled environment than just drinking caffeinated beverages on your own schedule.