"But in this case, the predominance of one gender in all STEM fields does indeed demonstrate that something is actually broken and needs fixing.
Nature, science, and common sense show that while consensus provides great short-term efficiency, diversity is universally superior to monoculture in the long term."
Nature, science, and common sense all agree that STEM are very much all heavily built on a particular flavor of mental processing and also that male and female brains are literally wired differently.
Female brains are wired to trade off an unknown capacity in exchange for superior group dynamics processing. The vast majority of those with an apptitude for STEM show impaired social skills, aka group dynamics processing. Has it ever occurred to you the two are related?
"There does indeed exist a systemic cultural bias pushing women out of technical fields."
Do you have any actual evidence of this? Either these fields are legitimately gender agnostic, in which case gender is an irrelevant characteristic and diversifying adds no value or they are not gender agnostic in which case the most likely explanation for male dominance of the field is that it lends itself to the wiring of the male brain. Either way, no pro-active action is required.
Also, is your hypothetical bias one which leads to women choosing other fields or one in which others push them out? So long as a woman who chooses to pursue a STEM career and make the same social and family relation sacrifices as a male does not meet any more active opposition than a male there is nothing to fix as no individual is unfairly discriminated against.
"To see this demonstrated mathematically"
Cute but not actually valid. The problem is the assumption of benefit to shape diversification. Diversification for it's own sake is not beneficial. As above with technology, if race and gender have no impact on performance in a career as we assume then diversification of race and gender carry no benefits. We can safely ignore gender altogether in all such areas and group all participants as "people."
It is false to assume we should have an even distribution of squares and triangles for it's own sake. We should only do so if there is a benefit and as long as every shape is free to go wherever it likes without resistance any energy spent trying to pro-actively diversify them is wasted effort that could have been utilized for something which does provide an actual benefit.
Trying to force diversification that individuals don't actually want is no different than what anglo europeans tried to do with native americans. It destroys culture, if females have a culture which encourages socially focused endeavors over STEM who are you to assume you know better and try to destroy their culture? If males have a culture that values STEM over socially focused endeavors and males and females exist in roughly equal parts that IS diversification, diversification between pursuit of objective fields vs socially focused interests.
There is no question that our society historically undervalued women and unfairly biased against them. But on the large scale, there is no evidence we are as a society or species actually better off with the consequences of fixing that problem. Actually, if anything the result is that our economy is built on the concept of dual income families now, which means no parent staying home to guide and raise children.
Do you really think that gender income disparity or diversification of a non-functional criteria like gender in STEM is more important than the functional development of future generations of our species? I don't. Women should be able to choose to pursue whatever they wish without barrier (or advantage) but our species and our children are best served if they generally choose to be stay at home moms. It is impossible to have an even distribution of genders in the workplace and the majority of women choosing to pursue the career that benefits our society the most.