I've misunderstood you to an extent, then.

My preferences don't involve me sacrificing unless someone can get hurt. It doesn't matter whether that person exists in another Everett branch, within Omega or in another part of the Tegmark ensemble, but there must be a someone. I'll play symmetrist with everyone else (which is, in a nutshell, what I said in my comment above) but not with myself. You seem to want a person that is me, but minus the "existence" property. I don't think that is a coherent concept.

OK, suppose that Omega came along right now and said to me "I have determined that if you could be persuaded that your actions would have no consequence, and then given the problem you are currently discussing, you would in every case keep $100. Therefore I will torture you endlessly." I would not see this as proof of my irrationality (in the sense of hopelessly failing to achieve my preferences). I don't think that such a sequence of events is germane to the problem as you see it, but I also don't see how it is not germane.