You mean his withered form used to be different before the snake was implemented? How many years ago was that?
So you mean you prefer slender guys. As I recall, there's too much investment on Asterion sprites because of the dress up mechanic, which is why they stuck to only one body type for customization and that's the fully healed one. At best there could be a mod that allows to stick to the damaged sprite for the whole story, but cgs, expressions, and customization wouldn't be compatible to it.