Meaningless as in the word has literally no meaning, or as in the concept is unimportant?

The latter. I'm willing to say that there could be some state of reality that corresponds to 1 world splitting into 2 identical worlds, but I don't think that should factor into any utility function.

You haven't really given an argument at all for or against your value system, nor have I. As far as I know, there's no way to prove a value system is correct, because values are entirely subjective.

What I want to see is a rigorous argument for or against cryonics over popular value systems. I'm not sure that even EA over all existing universes would say to get it.

I will note that conventional wisdom (in cryonics) seems to be that selfish people should sign up, while my theory disagrees, so there is something to be analysed there.

Actually, it is associated with the measure claim, since the fulfilling lives could be caused by the universe splitting into two.

If my measure goes from , say, .1 to .05, and .05 universes cease to exist, that still shouldn't matter to my utility, as long as those universes that don't exist are exactly identical to the .05 that still exist with me.

When you say "universe splitting into two", it refers to 2 universes that evolve exactly the same. I can't gain something in one world in exchange for losing it in the other, or the 2 would be counted separately in my measure.

In your example of taking a pleasure and destroying worlds, every single person that would have led "fulfilling lives" with probability of X if I refuse the pleasure still leads fulfilling lives with the same probability of X. The only thing that changes is their measure, which doesn't change anything, not even probabilities, as long as all measures change together. So even an altruist towards all worlds could say that it doesn't matter how many copies of the exact worlds are, as long as the relative ratios are the same.