What Would Need to Be True
That the "dysgenic shaman" selection criterion is actually documented in Hayden's work and not just Stone Age Herbalist's synthesis [UNVERIFIED — Hayden's primary work not in vault]
That the warrior aristocracy / shamanic hierarchy alternation pattern holds in cases beyond the Mongol example — is this a general historical pattern or a selected illustration?
A case study where both models operate simultaneously in the same society, to see how the contest is managed — feudal Japan (daimyo vs. Buddhist monks) might be the cleanest example