I believe the basic premise is that there is nothing in biology that makes computer science more interesting to men than it does to women.

Since it is not an imbalance that can be pinned on biology (perhaps unlike an imbalance in world weightlifting records?), the cause of the imbalance must be somehow 'nurture' related. Even if we do not consider the imbalance itself to be problematic, the imbalance is considered to be the result of some sort of bias that is assumed to be problematic.

For example, fewer women in tech may not be considered problematic in and of itself (though I believe many people think that it is), but the existence of this imbalance may be evidence of systematic sexual harassment, which certainly is problematic.

I might be getting this wrong, so I welcome corrections.