I will say, I've had two logical problems with this whole thing: why would Amazon target content in a way that would reduce its own sales? That never did make sense. But at the same time, how could it be a glitch, given the policy email? And now--how could it be a hack, given that same email? This is the closest I've come to a plausible explanation.
ETA: Hack's a fake? "There's a guy claiming he abused Amazon's reporting system in order to get GLBT books removed from the sales rank listings. Since I have some pretension to technical ability, I figured I'd give his claims a test run. Summation: nope, you didn't do that, you liar you. Nice meta-troll, though."
ETA 2: An Amazon rep says it's not a glitch? Caveat: "It's also worth noting that some folks, like Deanna Zandt, believe that the reps may not know what they're talking about. 'I'm almost positive at this point that it was a scripted (automated) thing someone figured out how to exploit,' Deanna [said] via email."