In addition, the "immigrants as parasites" has a long and terrible eugenic history. Perhaps you unwittingly connected to that when making what probably seemed like a clever analogy (as my first sentence above says, I think the analogy points the wrong way).
The system is the parasite, not the immigrants themselves. They are, in fact, its victims, as they will fall under the same below-replacement-fertility trap. Again, as I wrote in my post: "giving the parasite economic system a new host to feed on" - the new host being the immigrants.
> They are, in fact, its victims, as they will fall under the same below-replacement-fertility trap.
You say “trap”, as if a below-replacement birth rate is somehow bad. Do you actually think that that is the case?