system
A chat on 4chan
human
As a result of evolution the human brain is biologically wired to seek healthy mates. 
'Uncanny valley' is your simian brain being repulsed by ugly unhealthy people.
gpt
Autists use less mimics and eye contact, i think it could cause someone to experience uncanny valley 

I think this is likely

I have yet to experience uncanny valley from ugly unhealthy people
I searched up all kind of body deforming sicknesses and never experienced it
human
Your simian brain is subconsciously making connections between what you see as uncanny valley and the unhealthy