I'm staying out of the debate on this, however:
Logic based on incomplete information can be wrong.
Scientists still know very little about how the brain (any brain works). What is instinct, really?? How does a chicken that was raised in an incubator and under a heat lamp know how to brood a clutch of eggs and care for her chicks? Just saying "instinct" does not explain it.
How is a memory stored?? Really, they can't explain it.
Does your friend have direct experience with various snakes? If no, then how can she say she knows? She hasn't tested her theory!