The whiteness of a skin disease has nothing to do with the whiteness of albinism, and nobody in ancient times thought of albino people as having a skin disease. Being albino was “exotic” and interesting, in most of the Middle East. Kings often had albinos at court, for instance.
Albino horses were a thing, and they still are. That kind of albinism was often a death sentence (there are some killer genes involved), so it was something that ancient people were concerned to avoid breeding.
The Bible didn’t start talking about lepers being people with pink eyes who can’t stand the sun, now did they? So why would you think they were talking about albinism?