At first I was thinking maybe he'd model a sona after an animal that has sentimental value to him, like a cat or a gecko (pets/former pets)...but I was also thinking due to his frequent dissociation and detatched sense of self he might have multiple sonas, or maybe even a sona that is a hybrid of numererous animals that he likes? Regardless, his sona would probably have grey tones and maybe he'd find a way to throw the static hair into the design since he seems to embrace it as a part of him. I can see this sona wearing a lot of comfy clothes
(kinda off topic, but he also seems like that kinda person that would like a tv-head object head sona?? but that isn't quite a fursona. oops)