Has anyone disputed them? This seems like a great example of an ad hominem attack--you haven't had to question their data, or their logic, just the fact that they've found an argument supporting their conclusions.

That's a good way to talk past people. If you're legitimately concerned with their views, this is a great opportunity to identify what flaws there are with this argument, instead of the ways you already disagreed with the conclusion.

I mean, think about this in terms of who is contributing to the argument. Vdare: "Here is some analysis of the data, revealing what may be surprising results!" You: "Like most people, I disagree with VDare's conclusions. I'm not going to address their arguments, and I'd like to warn others against doing so, too." Who is contributing, here?