This raises the question of why a man, using the term loosely in Matthews' case, won't take his own side in a fight.
I don't much care for the ad hominem argument, but in this case, looking at Matthews invites an observation: This guy couldn't hold on to his lunch money in grade school.
Might it be that Matthews hates himself, and his civilization, because he's too big a weenie and not enough man to mount the ramparts to defend that civilization himself? Perhaps he see in the old, assertive, masculine, Europe and what's left of it—the Europe of Wellington, Sobieski, and Don John, and before them, of Henry V, Charlemagne and Charles Martel—the kind of men with whom he could never compete?
Let's face it. The guy who solves abstract math puzzles and crunches numbers to Rage Against The Machine doesn't get the girl. And he doesn't win any fights. The wonks who counted FDR's and Churchill's beans didn't win World War II. It was guys like these two Johns, Basilone and Grayburn.
That said, as to whether young Matthews' claims in his open borders piece hold water, it's worth looking over The Washington City Paper's assessment, in 2012, of young Matthews' math ability: "The Statistical Illiteracy of Washington Post Wonk Blogger Dylan Matthews."