With some exceptions I downvote any comment that complains about downvotes. I'm not 100% comfortable about it, and I might change my approach, but so far rigorously applying the rules seems to be working. I'm willing to bet I'm not the only one to do so.

One imagines they do. I'm not sure that's what's going on here, though.

Why wouldn't exactly that be going on here? It's a grade-A downvotable, flaggable comment.

Jesus Christ.

Suppose he is being treated unfairly by the mods. Is that not worth complaining about?

I don't give a crap about some silly "downvote every comment complaining about downvotes" rule. Complaining about downvotes was frowned upon because people get inexplicably downvoted as a matter of course here, and the frequency of complaints was deemed sufficiently detracting to warrant being frowned upon. Being treated unfairly by the mods, however, is another matter entirely.

I haven't seen a preponderance of evidence suggesting the complaint was ill-founded, and the guy's tenure and comment history (what I looked through of it) do not suggest he's an ill-mannered troll, so I reserve judgement as to whether the complaint is in the wrong. Like any reasonable person would.