Why not link them the other way? The article claims that individuals who are stronger physically will try to claim socio-political highground, but it seems much more realistic to me to observe this data and say that people who aren't as competitive or interested in gaining from others don't have the bent to exercise their biceps.

A better experiment for this hypothesis would be to take these original subjects and have some of them adopt an exercise system and others to abandon one. Then test if ideologies actually change as a result of physical strength.