I am not questioning the number, but the explanation is moot.
I have noticed that US folks (companies) have some strange desire to treat anyone outside of white male group as some sort of victims, which is both insulting and is not based in reality. I don't know, maybe women in US feel differently, but again, that has nothing to do with SO and moderation, but general culture. I have noticed that some people try to play victim card purely because it will give them advantage, and maybe some even think that is so, but that is something they need to fix on personal level.
Also one of the explanations for low participation of women on SO is that they are afraid, but maybe they are just more thorough in their research and are better in solving problems on their own. I certainly used SO for years before I joined, but not because I was afraid, but simply because I didn't have the need to ask any questions. And when I joined I did that because I wanted to leave comment under one question about some high DPI bug, but then I needed 50 rep to do that, so I started answering...
Point is, that anything is possible and it depends on each individual. Painting everyone with the same brush based on some completely unrelated characteristic is pure nonsense.