Isn't that essentially an ad hominem?

Against which party? I don't trust Orwell's judgement -- fighting for POUM, and making the argument above, weren't the only errors he made -- and I don't think Gladwell should have trusted it either.

(But then, Gladwell wrote a book called _The World is Flat_ in 2000, and it was about free trade, not fundamentalism; he's not exactly someone who I look to as a paragon of good judgement either.)

POUM was anti-Fascist and anti-Stalinist. If you think it was an error to support such a party in Spain at that time, I'm afraid it says more about your judgement than Orwell's.

Anti-Stalinist isn't anti-Communist. (Sorry for the extremely late post, though.)

In addition to your misreading of Homage to Catalonia, you also misattributed -- the author you're looking for is Thomas Friedman.