You're right on why women struggle to enter games competitively, but to say "he's technically not wrong" is very dismissive. Dude legit believes women can never be pro or top 500 in OW because they're not as smart, that they will lose to males every time, and women play support because they can't compete on a mechanical level. Nothing of what he said implies what you wrote at all, it's just pure sexism on his part.
If you want to read an excellent article (which is also where I found out about gale btw), Jake from LGEvil/USA team in world cup wrote a very detailed analysis on why women struggle to get into shooters competitively, he makes lots of good points similar to what you said:
https://mindgames.blog/2017/08/19/women-in-esports/
Quick edit: My respect for Jake increased tenfold today, nice to have such impressionable people in the competitive scene. He also called gale in text chat "gale_woman_hater" at an alienware monthly once. That was neat.