I thought the very direct point he was making is that there's an small number of women who are exposed to CS at a young age and that's something that has to change.
You can perfectly get a job in some Big Co. even if you only started programming in college.
But startups in general (and in this case, YC) all want to hire the top 1%, so isn't it natural they are biased at the people with the most experience, because they believe that they are better (which is not necessarily true)?