It seems to me that you equate a self with rebirth, i.e. when one assumes a self, then one has to assume that there is a rebirth. Which is not correct, since ucchedavadins assume a kind of self which is mortal and doesn't get reborn after death. I'm not even sure if all sassatavadins claim that there's a moral retribution after death. There where people in the times of the Buddha who even claimed that it's OK to kill, since a soul and other elements are "stable as a mountain peak" and sword can't touch them (see DN 2).
The teaching of the Buddha is quite different, since he doesn't assume a self. Instead, he says that if there is a kamma then it works as a support for a new conciousness — just like a field is a ground for a seed. He also teaches that this support won't end because one wishes that to happen (now or at death, as ucchedavadins hope to). It will end only when the Noble Eightfold Path (which is a special type of kamma) is fully brought into being.
Bhagavaṃmūlakā no, bhante, dhammā...