He was explaining how being angry at Saletan et al doesn't make you irrational or incorrect when challenging his study sources or his conclusion(s).

You are correct. I did misread that passage.

Can you define ad hominem and find two or more examples of it in Metcalf's piece? Doubt it.

Ad hominem: argument against the man.

"Who are these two men? J. Philippe Rushton is the head of America's most dedicated subsidizer and promoter of eugenic research, the Pioneer Fund, which I have written about here. Arthur Jensen has spent the last 40 years arguing against "compensatory education," or the idea that programs like Head Start have any efficacy in alleviating black underachievement."