Our attitudes toward people with marginal conditions mainly reflect a deontologist libertarian (libertarian as in "free will", not as in "against government") model of blame. In this concept, people make decisions using their free will, a spiritual entity operating free from biology or circumstance. People who make good decisions are intrinsically good people and deserve good treatment; people who make bad decisions are intrinsically bad people and deserve bad treatment. But people who make bad decisions for reasons that are outside of their free will may not be intrinsically bad people, and may therefore be absolved from deserving bad treatment. For example, if a normally peaceful person has a brain tumor that affects areas involved in fear and aggression, they go on a crazy killing spree, and then they have their brain tumor removed and become a peaceful person again, many people would be willing to accept that the killing spree does not reflect negatively on them or open them up to deserving bad treatment, since it had biological and not spiritual causes.

Assuming souls exist, what's the difference between a brain tumor and an evil soul in terms of who "deserves" suffering (disregarding the argument that they deserve suffering because God said so)? At the moment of birth, neither one is chosen by the agent. If anyone was born with the same genetics, environment, and soul, they would make the same decisions throughout life.

Therefore, even if souls exist, that doesn't change any conclusions about consequentialist versus retributive justice IMO.