I'm beginning to think that LW needs some better mechanism for dealing with the phenomenon of commenters who are polite, repetitive, immune to all correction, and consistently wrong about everything.

The problem is quite simple. Tim, and the rest of the class of commenters to which you refer, simply haven't learned how to lose. This can be fixed by making it clear that this community's respect is contingent on retracting any inaccurate positions. Posts in which people announce that they have changed their mind are usually upvoted (in contrast to other communities), but some people don't seem to have noticed.

Therefore, I propose adding a "plonk" button on each comment. Pressing it would hide all posts from that user for a fixed duration, and also send them an anonymous message (red envelope) telling them that someone plonked them, which post they were plonked for, and a form letter reminder that self-consistency is not a virtue and a short guide to losing gracefully.