If I'm understanding you correctly, the expected/imagined/whatever thing is a red herring; your comment applies just as well to actual downvotes. 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?

Karma's purpose is not unrelated to this question. 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) then net downvotes indicate the community judges that a post is of negative value to the community. Tim might update away from his belief that the post is valuable based on that judgment. (And, relatedly, update away from it based on his expectation of that judgment for an unsubmitted post.)

Of course, you might say in turn that the judgment of the community (whether actual or expected) should itself not cause Tim to change his belief.