Though in your example it wasn't a problem because you only had two outcomes and one outcome was always the zero point.

I think my procedure does not run into trouble even with three options and other offsets. I don't feel like trying it just now, but if you want to demonstrate how it goes wrong, please do.

the upshot is that to really deal with the problem of offsets you have to (at least de facto) normalize the relative utilities, not the utilities themselves. (On pain of stupidity)

I don't understand what you are saying here.