That would seem to make closing the borders a win: Americans get higher wages and more automation. But it assumes that the immigrants themselves have absolutely no moral standing. Their lives aren't made better by the fact that America has automatic fruit picking machines.
This is linguistically misleading in a couple of ways. First of all, if we keep them out, they're not immigrants; they're foreigners who might become immigrants. Second, nobody is arguing that foreigners have no moral standing at all. Immigration restrictionists don't favor hunting them for sport, or bombing their countries at random for our own amusement. Everybody agrees that foreigners have some moral standing.
I think that Steve Sailer has it just about right when he argues for "citizenism" -- that is, American elected officials should tailor our domestic policies, including immigration policy, to benefit current American citizens. After all, we don't expect Mexico, or El Salvador, or Guatemala or even Canada to arrange their policies to benefit us, do we? Their elected officials are elected by their citizens to benefit that political community. Like it or not, until we put in place a world government, the nation-state is the fundamental political unit.
So the short answer to her question is no, the welfare of foreigners who might become immigrants doesn't count. I would arrange immigration policy to benefit current American citizens.
So what would that entail? I am perfectly willing to be convinced that the raw amount of immigration should go down, should stay the same, or even be increased. I'm not wedded to any particular one of these suggestions, but here's a rough cut.
To begin with, most illegal immigrants are unskilled, and, on average, are going to end up being tax-eaters rather than tax-payers. Dramatically reducing illegal immigration has to be top priority. Obvious first step: use physical barriers to seal the border with Mexico. Authorize Border Patrol Agents to use force, including deadly force, against illegal immigrants. It's clear we cannot deport ten or twelve million illegals in one go, but we can streamline the hearing process and hire more immigration judges.
After that, there's a lot we can do to make self-deportation a more desirable choice. Make it a felony to knowingly provide any material assistance to any illegal immigrant -- and by "any material assistance" I mean so much as a glass of water. Certainly setting up a place for day laborers to hang out counts, if you know that lots of them are illegals. Require states and municipalities which receive federal money to cooperate fully with federal immigration authorities. Bar illegal immigrants from receiving any government assistance of any sort.
Once that's done, it's fairly easy to reform the system of legal immigration. To begin with, get rid of chain migration by scaling back family reunification. Limit it to minor children and spouses, not parents, adult children, cousins, nephews, aunts, or uncles. Then select immigrants based on whether they are likely to be tax-payers rather than tax-eaters. As a first approximation, we should look for English fluency, and either scientific or technical skills or demonstrated business acumen. Smart students we let in, even if they are likely to remain in the United States after graduation. Particularly if they are likely to remain in the United States after graduation.
Finally, the United States should actively encourage "brain drain." Not only should we allow the smartest, the most innovative, the most productive people in the world in, but the United States should target, say, ten thousand people a year for active recruitment. We are not competing for land or resources these days, but we are competing for the ultimate resource: brains and talent. So the United States should design its immigration policy with that goal in mind.