Equal opportunity does not necessarily mean equal interest. A complete lack of sexism does not necessarily mean equal interest. You are following the assumption that there would be 50/50 proportions of interest (and therefore skill, and therefore employment) just because a field meets all your criteria of "not sexist". This is an unfounded assumption. No matter what the situation, there is never a guarantee that equal amounts of men and women will be interested in a particular field -- and this is not necessarily a product of a flaw in the field, but could be indicative of societal inertia (things go in and out of fashion with different groups), biological differences, or just random variation.

The first question we must ask is -- if there is a gender divide, why is there a gender divide? The second question we must ask is, is the reason for it actually problematic? do we have evidence that it is sexism? If it is a problem, we must ask can we solve it without causing bigger problems?

It seems we have missed most of these questions, assuming the reasons for the gender divide, assuming that it is sexism, and not considering if our solutions will just cause more problems. This is simply irresponsible. It makes us prone to unnecessary disruption, and our inclination to jump to sides -- either side -- doesn't help.