I would disagree on your point that "knee-jerk anti-US comments are karma gold here" on 2 notes, 1 that being anti-US-administration is not being anti-US, and 2 that most unsubstantiated comments that are critical of government actions almost always get down voted to oblivion.

Everyone knew that North Korea had it out for Sony, what's to stop a network security enthusiast from stirring the pot by performing the attack and planting "evidence" that it was coming from North Korea. I don't think it's far fetched to think that many young security enthusiasts would get excited to think about causing such a stir.