I haven't answered your objections to my style of moderation, but it isn't because I haven't been thinking about them. Unfortunately, I don't think I can manage the sort of clear boundaries I think you prefer.
The good news is that I'm extremely unlikely to want to ban you. You have a civil approach, and part of what gets people banned is lowering the tone or if you prefer, being a pain in the ass.
The hard thing is that there doesn't seem to be a good way to discuss the emotional effects of statements-- the only way to evaluate emotional effects is by what people say those emotional effects are, and in addition to whether you trust what people say about their emotions, language is ambiguous that there are frequently alternate interpretations, especially when the underlying question is how much of a welcome people feel in a venue. It might be more efficient to say that claims about emotional effect are entangled with implied claims about who's in charge and who matters.
The bad news is that I'm not at all sure I can formalize this, though my net gain in karma in this discussion suggests that I have an accurate sense of what LW is, even if it's possible that LW could be improved with a more open attitude about abhorrent viewpoints. (I don't think it would be an improvement, I'm just saying I acknowledge it's theoretically possible.)
Just getting a clearer idea of what is abhorrent and what isn't might help, but I really do think part of the problem is tone. There are policies which are vile no matter how abstractly and politely they're expressed (for example, slavery on a grand scale), but the amount of hatred added to policy adds an emotional sting.
I've gotten sufficient evidence from support that voiceofra has been doing retributive downvoting. I've banned them without prior notice because I'm not giving them more chances to downvote.
I'm thinking of something like not letting anyone give more than 5 downvotes/week for content which is more than a month old. The numbers and the time period are tentative-- this isn't my ideal rule. This is probably technically possible. However, my impression is that highly specific rules like that are an invitation to gaming the rules.
I would rather just make spiteful down-voting impossible (or maybe make it expensive) rather than trying to find out who's doing it. Admittedly, putting up barriers to downvoting for past comments doesn't solve the problem of people who down-vote everything, but at least people who downvote current material are easier to notice.
Any thoughts about technical solutions to excessive down-voting of past material?