The pilot's abilities, or so I read, were based on speed/dexterity, enhanced reflexes, and other things that alien species had as an advantage... Not really size. Or so was my understanding... Thus Anakin could have grown to be his full height and STILL flown a pod because of his reflexes from the force over his stature.
By that standard, either Mawhonic was abnormally gifted for his species, or his race of Gran is gifted with those attributes, or all Grans are gifted with those attributes and Ree Yees is just stupid.
Or he has the force in him too and Qui-Gon is anti-Gran?