As a layman reading the paper, my understanding is that greater male variability has already been observed in "personality, coginitive abilities, and school achievement". The question here whether and to what extent that variability is due to "early life genetic or gene-environment interaction mechanisms". The implication of this paper seems to be that since pervasive brain-structure differences in variability can be observed throughout the lifespan of individuals, the variability in high-level traits are likely to have strong genetic component.
The introduction in the paper focuses on the "downside" of high-variability in males (their propensity for neurological disorders). Unless I've missed it, any "upside" to high-variability was left unstated.