It's possible he's right that there's absolutely nothing more he could do. I think it's extremely unlikely, though. If women feel uncomfortable in YC-funded companies, I think that's a problem he could address. If women feel uncomfortable in the culture surrounding YC, I think that's another problem he could address. It's very un-hacker-like to, when confronted with a problem, throw your arms up in the air and proclaim there is nothing more you can do.