the essence of Douthat's argument is that progressives are in favor of access to abortion, and abortion can be used for eugenic purposes, therefore progressives are in favor of eugenics. This is ridiculous for reasons that have nothing to do with the motives behind particular abortions. It's like saying that if you oppose banning guns, you're in favor of bank robbery, hunting bunny rabbits, and suicide.
No. It's like saying "if you oppose banning guns, and you also oppose any efforts to prevent bank robberies, then you effectively support the spread of bank robberies." Which I think is a reasonable way of looking at it. Or more accurately still (because a gun and an abortion aren't the same kind of thing at all), it's like saying "if you believe in an unfettered right to theft, then you effectively support the spread of bank robberies." In the case of Gattaccagenics, that's where the logic of Roe-style reproductive rights will carry progressives, I predict - to open-ended opposition to any attempt to restrict genetically-selective abortion and (eventually) genetic engineering in utero, whether it's intended to eliminate Down's Syndrome today, or autism tomorrow, or homosexuality or a predisposition to cancer or what-have-you the day after that.
But look, this much Ezra and others have right: What you think about Gattaccagenics is going to be deeply influenced by what you think about the morality of abortion. Yes, there are plenty of pro-choice, anti-Gattaccagenic voices out there, from Michael Sandel to (surprisingly) Leon Kass. But the more you accept pro-choice premises, the more likely you are to share the point of view expressed by the other commenter Ezra quotes - namely, that aborting fetuses with genetic abnormalities is no different than two people at risk of passing on a genetic disorder to their offspring choosing not to procreate in the first place.
*You may notice that Gattacca's Wikipedia page describes the movie as a "vision of a society driven by new eugenics," even though there is no state coercion of reproduction or forced sterilizations of minority groups depicted in the film. I hope Ezra or Kevin Drum will move quickly to correct this egregious Godwin's Law violation, which was doubtless planted by the same "bright boy or girl in the conservative movement" who whispered the term "eugenics" in my ear in the first place.