So if there was the threat of everyone having to race to clone themselves as much as possible for more influence, it might modify itself to give clones less weight, or prohibit cloning

Prohibiting these things, and CEV self-modifying in general, means optimizing for certain values or a certain outcome. Where do these values come from? From the CEV's programmers. But if you let certain predetermined values override the (unknown) CEV-extrapolated values, how do you make these choices, and where do you draw the line?