Cowen enjoys this kind of rhetorical maneuver, I suspect largely because there's nothing that pleases his ego more than to think of himself as not only smarter than liberals, but smarter in a much more unconventional way than liberals. By this standard, Cowen's post of this morning probably caused him to spontaneously ejaculate on his keyboard.
But anybody with an iota of ability to connect abstract ideas to the real world should intensely question a definition of welfare by which a "typical 23-year-old lower-middle-class immigrant has a higher real endowment than does Warren Buffett". In fact, I think you can find this sentence in the dictionary under reductio ad absurdum
And yes, I know what Cowen's referring to when he talks about McKerlie and egalitarianism. I do not find McKerlie convincing. It's the height of arrogance for Cowen to blithely assume that those who disagree with him are either confused about his argument, ignorant of the background, or irrationally rejecting a sound argument for emotional reasons, rather than simply disagreeing about the highly arguable philosophical conjecture which provides the foundation of his argument. Cowen's usually worth reading, but every once in a while all of his personal and intellectual flaws come crashing together in one horrible post that makes me want to get him banned from every restaurant on the planet.