You seem to be equating saving someone from death with them living literally forever, which ultimately appears to be forbidden, given the known laws of physics. The person who’s life you saved has some finite value (under these sorts of ethical theories at least), presumably calculated by the added enjoyment they get to experience over the rest of their life. That life will be finite, because thermodynamics + the gradual expansion of the universe kills everything, given enough time. Therefore, I think there will always be some theoretical amount of suffering which will outweigh the value of a given finite being.
You seem to be equating saving someone from death with them living literally forever, which ultimately appears to be forbidden, given the known laws of physics. The person who’s life you saved has some finite value (under these sorts of ethical theories at least), presumably calculated by the added enjoyment they get to experience over the rest of their life. That life will be finite, because thermodynamics + the gradual expansion of the universe kills everything, given enough time. Therefore, I think there will always be some theoretical amount of suffering which will outweigh the value of a given finite being.