If the natural analogy doesn't appeal to you, consider any organization of which you are a voluntary member--professional organizations, etc. These organizations set the standards for who may join and who is excluded. You probably approve of this. Certainly no one is arguing for illegal enrollment into the bar, for instance. Why, then, do some support illegal immigration? I consider the community of Americans to be far nobler than the aforementioned organization, and I believe we should define the requirements for joining this community and enforce them.
I like your cell analogy.
Would you say she has pink blood? As she is full of Homoglobin?
How’s your brother, Keyser??