Paul Graham isn't keeping women out of technology. Nor do I believe he wants to. If anything, his interests would be served by there being more women in technology, and thus more candidates for YC.
Also, Valleywag is a cesspool. I ponied up for the whole interview at The Information. I'd rather eat a bug than talk about what a Gawker publication has to say.
But Paul Graham has said some things on this issue that I think are dumb. Moreover, I believe he spends a lot of time worrying about the ways things he says are misconstrued. Reputation is potential energy, as he (correctly) likes to say, and I think he's aware of how much energy is tied up in what he says. Knowing that he is speaking carefully on these issues does not make what he is saying easier to take.
It is one thing to suggest that we should correct biases and imbalances as early as we can, because the sooner someone gets started hacking, the sooner they'll be able to bring those skills to bear on the market. Sure, that's true and probably benign.
It is another thing entirely to suggest that special status is conferred on people who started hacking when they were 13, and that it might be "too late" for people who didn't to join the ranks of that elite.
It is one thing to suggest that there are people that have, for whatever reason (nature or nurture) a natural affinity to working with computer programs and technology. True. Benign.
It is another thing to project backwards from that the idea that if women were going to be good at coding, "they would have found it on their own". That's not true. It presumes that the most important factor in determining whether someone's going to be a good coder is that they have the affinity. But you need more than affinity: you need opportunity and support.
A gigantic blind spot men in technology have is that there are two sides to the problem of gender bias. The side of the coin everyone thinks about is prejudice and bias. Men hear about gender imbalance in technology and interrogate their conscience. "Do I think women are inherently less qualified then men? No! I've never made a decision based on that belief!" They're probably even right about that.
The coin has another side: privilege. Privilege is a simple concept. Certain kinds of people "fit the mold". Paul Graham knows what the typical successful startup hacker looks like. So do most people who work at technology companies. If you ask someone in our field at random to visualize an elite startup hacker and then take bets on the attributes of that imaginary person, you would be nuts to bet on anything but "male", "English-speaking", "20-40", and "white or Asian".
25-year-old English-speaking white males have a privilege, whether they like it or not, because they fit into everyone's mold of a startup hacker. They will sometimes be asked stupid, discouraging questions at job interviews. Like, "do you have any children, and, if so, how will you balance the work of taking care of them with the demanding schedule of this job?". Or, "when did you start coding? We're really looking not so much for someone who can execute this role, but rather who lives and breathes technology". You can tell by looking at some people that they "live and breathe technology" (guilty as charged). That's not a privilege at a bar or a White Sox game, but it is a privilege in our industry.
The existence of privilege is not a scarlet letter on young white dudes who code. But the forceful, repeated, insidious denial of the existence of that privilege is a problem: it reinforces the privilege and allows it to feed on itself.