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Being harder science fiction, the idea that a "fluid" designed to operate alien technology could do something as improbable as mutate a person into an alien breaches the hard science reality the movie has established. Shooting myself up with dog dna, sleeping in a dog bed, or doing other dog related stuff doesn't turn me into a dog. Specific, controlled mutations as an unintended consequence of an accidentally administered substance are inconsistent with the hard science the movie has tried to establish. The movie doesn't allow for for this to be a realistic possibility.
It's not a man-made fluid, it's an alien-made fluid. Who's to say the fluid isn't made out of something similar to the HIV virus, where instead of taking over T-cells and eventually destroying the immune system it hijacks all your cells and mutates your dna to match theirs?