What a strange coincidence [...]

The equivalence I think you're appealing to doesn't look real to me. Let's suppose you're right about what's happened to advancedatheist: he posts something with a particular political/social leaning, lots of leftish people don't like it, and they pile on and downvote it into oblivion. Contrast with what Eugine is alleged (with good evidence, I think) to have done: someone posts something with a particular political/social leaning, Eugine doesn't like it, and he downvotes 50 of their other comments. Two key differences: (1) In the first case, the thing getting zapped is the comment that these people disapprove of; in the second, it's a whole lot of comments there's nothing wrong with even by Eugine's lights other than who posted them. (2) In the first case, each person is downvoting something they disapprove of; the total karma hit advancedatheist gets is in proportion to the number of disapproving people and the number of disapproved comments; in the second, Eugine is doing it all himself; the total karma hit his target gets is limited only by Eugine's patience.

"I would like him to shut up and go away"

No doubt it's very disagreeable to want someone to shut up and go away. But rather than cherrypicking those 10 words, let's take a look at the context -- which seems to me to have (again, by coincidence) two key differences from that of EN's karmattacks. (1) philh is making a very specific accusation about advancedatheist: that he is not participating here in good faith because he seems only really to be interested in popularizing PUA, even in discussions that have basically nothing to do with it. I don't know whether philh is right or wrong about this, but I'm pretty sure Eugine couldn't and wouldn't have claimed with a straight face that the people he karma-bombed here are (e.g.) only posting to spread left-wing ideas or feminist ideas or whatever. It seems to me that there's a big, big difference between "X is on the wrong side politically; therefore, I would like him to shut up and go away" and "X is trying to force his pet single issue into every discussion on LW and contributing little else; therefore, I would like him to shut up and go away". (2) What philh is owning up to doing to advancedatheist on account of this is not the same as what Eugine is alleged to have done to lots of people. Eugine: downvoting dozens of comments merely because they're posted by one of his targets and afford an opportunity to inflict downvotes. philh: being quick on the trigger when he sees a low-quality comment from advancedatheist. Again: big difference between "I would like X to go away, so I'll downvote all his comments until he does" and "I would like X to go away, so when he says something I think is of low quality I'll downvote it more readily than I would a similar comment from someone else".

For the avoidance of doubt, I am not endorsing the behaviour I think philh has admitted to here. I think it would be better if he didn't do it. Someone who's abusing the community by spamming LW with single-issue stuff is going to get downvoted to hell purely on his comments' actual merits, with no need for the itchy trigger finger, and that's a good thing. (And I think it's what's been happening to advancedatheist.)

I was involved in exactly the kind of case you posit, where someone basically cast conservatives as in league with Lucifer

No, he really didn't. Not remotely. This is the article in question. (Right?) There's nothing there remotely like casting conservatives as in league with Lucifer. What there is -- and I think this is what Kaj later agreed you were right about -- is something much less stupid, less harmful, and less likely to be the result of ill will: in one place he gave an example involving social conservatives' thinking about liberals' legislative preferences regarding homosexuality, and he didn't do a very good job of getting inside social conservatives' heads, and consequently his description was inaccurate and made them sound sillier and more unreasonable than they (typically) actually are. That's all.

(To put it differently: I suggest that nothing Kaj wrote was any more inaccurate or uncharitable than your description of him, just now, as having cast conservatives as in league with Lucifer.)

In any case, Kaj's article is irrelevant here, and would be even if he'd been much ruder about social conservatives than he actually was. Because JoshuaZ's complaint about advancedatheist is that he shoves highly-charged political asides into comments about other things. Whereas Kaj's whole post was, precisely, about how people think about their political opponents. No matter what he said there, there's no way it could have been an example of the behaviour JoshuaZ is criticizing advancedatheist for.