The androids are alien-like enough because of their white blood, despite looking like humans. They make Alien stand out further in horror. One of the prominent features in the franchise is how the aliens forcing their offspring onto humans is a metaphor for sexual attacks.

The androids having white blood further develops this metaphor. The aliens are not the only sexual attackers; but the androids are too. The white blood symbolizes the bodily fluid that manifests from these attacks, which increases the horror of the franchise. If their white blood is contained, they are not a threat. If it is showing, then they are.

The white blood used in Alien is actually milk. The Alien franchise already stands out as a horrifying creature feature. The cherry on top of it all is the androids and their white blood. At least the aliens are clearly the villains because of their grotesque figures. The androids are not so obvious unless they are already wounded.

Without the androids and their discomforting white blood, the Alien franchise would not be as scary as it is. Alien 's androids think, feel, and look like humans. To be distinguished as separate villains or heroes, they need a particular quality to set them apart.