I consider it self-evident that Sam_sunday should be allowed to arrange for Sam_monday to be tortured without the ability to make it stop, and by the same token Sam_monday should be allowed to do the same thing to Sam_tuesday_x.

I reject the premise. Why should it be self-evident that Sam_sunday should be allowed to arrange for Sam_monday to be tortured? Doesn't this seem like something people only came up with because of the illusion of subjective anticipation?

EDIT: I just read what you wrote in a different comment on this post:

I don't actually care about the avoidance of torture as a terminal moral value.

You statements make sense in light of this. My morality is much closer to classical utilitarianism (is that the term?) and may actually be classical utilitarianism upon reflection. I assumed that you did care about the avoidance of torture as a terminal value, since most LessWrongers do. Torture is often used as a stock example of something that causes disutility so, if you are presenting an argument, you will often need to mention this aspect of your value system in order to bridge inferential distance.