It's "offensively wrong" because the author (a male) is striving for an image of being genuinely sympathetic to The Plight. "Look at me, I'm so understanding."
'Disingenuous' isn't quite the word I would use. I'm sure the author really does think he's contributing to The Crusade, which is precisely the problem. He can't just dissect the errors in Arrington's logic. No, that's not good enough.
He needs to put on a Crusader uniform and act like he thinks those people are supposed to act: offended. He can't just BE offended, he must explicitly tell you he's offended, and start swinging his sword around so you know what a noble Crusader he is.
If he were responding to a blog post offensive to men, would he have used that language? No, because being offended for yourself isn't noble, it's being offended for others. And telling everyone about it as much as you can. How else will people know what an altruist you are?