Because compared with bench-pressing, claims of mathematically ability being better in men (and partially ordered, to boot) is seriously jumping the gun.

We know what's involved in a bench press. We understand how testosterone stimulates the production of muscle. We are nowhere close with mathematical ability. We have no theory of mathematically ability -- we really don't know what it means, or if the simplest metrics are even useful for higher level math. We have no experimental results, because we have no controlled variables. We have few pieces of data, none of which are conclusively disentangled from cultural and historical influence.

In the past two decades, the number of women scoring highly on the IMO, the IOI, the Putnam, and SMPY has gone up by roughly a factor of six. Doubtful that the number of girls with 'math talent genes' have sextupled that quickly. Isn't this evidence that we should hold off on our conclusions?