I think Kaj is trying to do a job he does not particularly want to do. I think that because he has said that is what is happening and even though he might be signalling, I tend to think that rationalists I respect are usually telling it straight.
I think he is acquitting himself honorably and intelligently, even if I don't particularly agree with the result.
My own values around rationality include the avoidance of stating inaccuracies in the name of signalling. They include not going "over the top" in response to "rule breaking" especially when the rules were not incredibly clear ahead of time. They include living by the consequences of the rules you do set up, so if people need to earn the right to downvote, and having earned it do something which is unpopular but was not explicitly against the rules, then going for a permanent ban AND pre-committing to hold your hands over your ears and scream (so you can't listen) if people start discussing why this might be a bad idea would seem to me to be a bad approach.
If I were the mod, and I'm not, and I will never have nearly enough popularity/karma to be tapped on the shoulder, I would ban Eugine until he agreed not to do massive downvoting anymore. If he chose to stand on principle (whatever principle that might be) and refuse, then he would be banned as long as he felt that way.
Another advantage of an approach like that is Eugine could be asked as part of staying on site to go through and reverse all of his own downvotes. It is not that hard to page through your own comments, see the ones you have downvoted, and click your downvote, cancelling it.
If he were willing to agree not to do it again, and to go through and reverse what he had done, that would seem to suggest to me he should stay around. It would also solve the problems "we" still have of 1) how do we stop him from doing it again and 2) how do we go about reversing what he has done.
Another advantage of an approach like that is Eugine could be asked as part of staying on site to go through and reverse all of his own downvotes.
If Eugine would have prefered that course of action like that he could had offered it himself in his response to Kaj. Eugine is smart enough to be able to have responded to Kaj's inquiry in a way like that if he wanted to do so. If he would have I doubt that Kaj would have banned him.
As previously discussed, on June 6th I received a message from jackk, a Trike Admin. He reported that the user Jiro had asked Trike to carry out an investigation to the retributive downvoting that Jiro had been subjected to. The investigation revealed that the user Eugine_Nier had downvoted over half of Jiro's comments, amounting to hundreds of downvotes.
I asked the community's guidance on dealing with the issue, and while the matter was being discussed, I also reviewed previous discussions about mass downvoting and looked for other people who mentioned being the victims of it. I asked Jack to compile reports on several other users who mentioned having been mass-downvoted, and it turned out that Eugine was also overwhelmingly the biggest downvoter of users David_Gerard, daenarys, falenas108, ialdabaoth, shminux, and Tenoke. As this discussion was going on, it turned out that user Ander had also been targeted by Eugine.
I sent two messages to Eugine, requesting an explanation. I received a response today. Eugine admitted his guilt, expressing the opinion that LW's karma system was failing to carry out its purpose of keeping out weak material and that he was engaged in a "weeding" of users who he did not think displayed sufficient rationality.
Needless to say, it is not the place of individual users to unilaterally decide that someone else should be "weeded" out of the community. The Less Wrong content deletion policy contains this clause:
Although the wording does not explicitly mention downvoting, harassment by downvoting is still harassment. Several users have indicated that they have experienced considerable emotional anguish from the harassment, and have in some cases been discouraged from using Less Wrong at all. This is not a desirable state of affairs, to say the least.
I was originally given my moderator powers on a rather ad-hoc basis, with someone awarding mod privileges to the ten users with the highest karma at the time. The original purpose for that appointment was just to delete spam. Nonetheless, since retributive downvoting has been a clear problem for the community, I asked the community for guidance on dealing with the issue. The rough consensus of the responses seemed to authorize me to deal with the problem as I deemed appropriate.
The fact that Eugine remained quiet about his guilt until directly confronted with the evidence, despite several public discussions of the issue, is indicative of him realizing that he was breaking prevailing social norms. Eugine's actions have worsened the atmosphere of this site, and that atmosphere will remain troubled for as long as he is allowed to remain here.
Therefore, I now announce that Eugine_Nier is permanently banned from posting on LessWrong. This decision is final and will not be changed in response to possible follow-up objections.
Unfortunately, it looks like while a ban prevents posting, it does not actually block a user from casting votes. I have asked jackk to look into the matter and find a way to actually stop the downvoting. Jack indicated earlier on that it would be technically straightforward to apply a negative karma modifier to Eugine's account, and wiping out Eugine's karma balance would prevent him from casting future downvotes. Whatever the easiest solution is, it will be applied as soon as possible.
EDIT 24 July 2014: Banned users are now prohibited from voting.