Google does not employ men and women, the general abstract averages. It employs specific men and specific women, who have demonstrated specific skill sets that make them just as able to do their specific jobs.

Consider an analogy, if you would. Surely we agree the average man is a faster sprinter than the average woman. Surely we agree the fastest man is a faster sprinter than the fastest woman. But it is still possible to staff a sprinting team of those who can beat an arbitrary non-fastest time (say 30s in the 100m) with any arbitrary gender ratio. Such a sprinting team whose ratio was 90% male could not, therefore, resort to biology to explain that disproportion, because the biology is manifestly not relevant.