The author did not state or imply that his co-workers were undeserving of their jobs. He was simply stating that biological differences may influence one's career ambitions.
For example: Women tend to be more empathetic than men, and this may have something to do with why they're more likely to pursue psychiatry as a profession than men.
This statement does not imply that men shouldn't pursue psychiatry, just that they're probably less likely to do so. I don't see how that statement is sexist.
> affirmative action is practiced in colleges while companies practice seeking diversity out of the same pool of qualified applicants
I'm not sure what the difference there is. Google calls itself an "affirmative action employer", and thus likely engages in the same kind of affirmative action that colleges do.
It's unfortunate that you've been the brunt of such prejudices. But as long as affirmative action is conducted the way it is (discriminating in favor of underrepresented minorities), those prejudices will always exist.
A better and more fair way of promoting diversity is to keep the interview process strictly meritocratic and gender/race-blind, but engage in initiatives that help prepare underrepresented minorities (ideally from low income backgrounds) for the interview process and encourage them to apply. My one stipulation would be that these programs should be open to anyone, rather than being restricted by race/gender.