There are many ways to argue for something like "this is weak methodology" and some of them are fallacies. Some of them aren't. A good argument against a study

There are many ways to argue for something like "this is weak methodology" and some of them are fallacies. Some of them aren't. A good argument against a study's methodology would probably talk a lot more about the methodology, and a lot less about a believable alternative narrative that is supported by the study. The latter strategy is accepting of the methodology because it is granting that the observed effect is real and deserving of explanation. In a different light, the earlier comment ("As an example of how the observed differences could still be due to nurture rather than nature...") is kind of weird because it is as though the effect might as well be due to nature -- it would present the same way and be as consistent and robust -- even if it were due to socialisation.