Actually, you might remind him that bikes steer by leaning, not by manhandling the handlebars ;-) (Consider all those folks who ride "no hands.")

I usually ride on 700C wheels, but also have a Bike Friday Tikit with 16-inchers, which is very maneuverable. That has a whole lot more to do with the fact that the Tikit has very little trail, and a short wheelbase than the actual size of the wheels.