That reason reeks of intolerance. It was used to suppress entire populations.

No, that's just silly. A community can enforce minimal standards of acceptable behavior without "suppressing entire populations." Let's not invoke Godwin's Law over one annoying troll. That's simply an argument for having no standards at all.

Downvotes achieve nothing.

Maybe that's the point we're trying to make by using them.

Look, we've had this discussion before. We tried ignoring him. The problem with that is it leaves him free to post his nonsense unopposed where newbies will find it and be misled or driven away from Perl. That's no good for a programming help site that can be entered at any node from search engines. We've tried reasoning with him, but he's not interested. If we bring up banning him, or even reaping his posts, that's shot down as censorship. You just argued that downvoting his posts is tantamount to "suppressing" people, but you'd support outright banning him? That seems backwards.

So all we're left with is downvotes and explaining why he's wrong. Over and over. Day after day. Year after year.

If you have a better solution, one that hasn't already been tried and failed or suggested and shot down, and that won't make people faint at the spectre of censorship or suppression, please offer it. The community needs it.