the expected/imagined/whatever thing is a red herring;

It's not a red herring, it's another reason.

Your claim is Tim ought not take downvotes into consideration when evaluating the value of a post, whether they be expected downvotes on expected posts, imaginary downvotes on imaginary posts, or actual downvotes on actual posts.

Yes?

No. Downvotes are information. Don't ignore them. But don't let them keep you from what you consider the right thing. The context was of him not posting what he considered quality material, anticipating downvotes.

If net karma approximates an expression of the community's judgment of the value of the post to the community (which it's supposed to, though it's not clear it does)

I don't suppose that at all. Do you?