There is a difference between "parliament should always be 50/50" and "parliament has always (until today) skewed in one direction, that suggests a problem".
EDIT: To support my position, here are some non-biological factors which affect the proportion of female politicians: https://en.wikipedia.org/wiki/Women_in_government#Challenges...
Neither of which is true. The implicit and explicit biases are common to both/all genders.
I mean, that depends to some extent on the source of that thinking.
Why even bring up women voters? Are you suggesting the 50/50 split is now because women voters have female candates to vote for?
The electorate chose a 50/50 parliament. We have no idea whether it was mostly men who voted for women or whatever it was.