Preference plays a role. Also, there is evidence that preferences differ between the genders and are not entirely due to social, political, or cultural reasons.
The argument holds true for innate preferences as well. It's one thing to argue that some preferences are innate in men versus women, another thing to prove that these preferences would cause women or men to avoid tech more than their counterpart on average in a vacuum, and a particularly extraordinary thing to prove that the "optimal equilibrium of gender" in tech is significantly different than 50/50 because of both of the above.
It would be difficult to prove any "optimal equilibrium of gender" even one of 50/50. Of course, those who strive for equality of opportunity aren't trying to institutionally force their optimal equilibrium of gender on anyone else. We accept that preferences play a role as to who ends up working in a particular sector, and those preferences may differ from our ideal.
Preference plays a role. Also, there is evidence that preferences differ between the genders and are not entirely due to social, political, or cultural reasons.