I don't think his torso is so short. His shoulders, i'll admit, are very, very wide. (As we know, advertising art of this era was never so hot at accurately portraying th male physique.) The trousers in the picture are particularly high waisted, i'll grant you - on or around the bottom rib, at a guess. This figure would perhaps be based on a very tall and athletic man, maybe a Gary Cooper type?
Most of my trousers waistbands sit between the navel and the bottom rib, aiding in the creation of the effect shown in the drawing.
bk