Would it be morally unreasonable for citizens of the society to decide whether immigrants should have rights equal to established citizens' rights, based on factors such as the benefit-burden approach presents (i.e., based on how much their having such full-fledged rights would impose on the full-fledged citizens, how badly off the immigrants are in comparison to how they otherwise would have been if they are not fully protected, what risks for benefits we might expect them to bear, etc.)?
This response to the objection can be understood better if we consider another objection to the argument: If people come to our country to escape an undeserved threat of death, we do not send them back. They are allowed to stay. (An undeserved threat of death is not the same as an unjust threat of death. The fetus does not deserve to die, but we must not prejudge the permissibility of abortion by comparing its death with what is assumed to be an unjust killing of a refugee.) Is this not analogous to the case of the fetus who will die if it is not allowed to stay? Not entirely. The case of the fetus is, rather, analogous to a case in which the refugee escaping an undeserved death requires not mere residence in this country but residence in the body of one of its residents. Specifically, may the state require that a resident place the refugee in his body for nine months, as the alternative to sending him back, if citizens do this for each other?