Here he is recently at the NYT:
...Over the past 30 years, a large fraction of immigrants, nearly a third, were high school dropouts, so the incumbent low-skill work force formed the core group of Americans who paid the price for the influx of millions of workers. Their wages fell as much as 6 percent. Those low-skill Americans included many native-born blacks and Hispanics, as well as earlier waves of immigrants....The National Academy of Sciences recently estimated the impact of immigration on government budgets. On a year-to-year basis, immigrant families, mostly because of their relatively low incomes and higher frequency of participating in government programs like subsidized health care, are a fiscal burden. A comparison of taxes paid and government spending on these families showed that immigrants created an annual fiscal shortfall of $43 billion to $299 billion....Similarly, the ideological climate that encouraged assimilation back then, neatly encapsulated by our motto “E pluribus unum” (Out of many, one), is dead and gone. A recent University of California directive shows the radical shift. The university’s employees were advised to avoid using phrases that can lead to “microaggressions” toward students and one another. One example is the statement “America is a melting pot,” which apparently sends a message to the recipient that they have to “assimilate to the dominant culture.”
Europe is already confronting the difficulties produced by the presence of unassimilated populations. If nothing else, the European experience shows that there is no universal law that guarantees integration even after a few generations. We, too, will need to confront the trade-off between short-term economic gains and the long-term costs of a large, unassimilated minority.
He points out that Trump's answer to the immigration question is to put Americans first, and asks a poignant question.
Many of my colleagues in the academic community — and many of the elite opinion-makers in the news media — recoil when they hear that immigration should serve the interests of Americans. Their reaction is to label such thinking as racist and xenophobic, and to marginalize anyone who agrees.But those accusations of racism reflect their effort to avoid a serious discussion of the trade-offs. The coming debate would be far more honest and politically transparent if we demanded a simple answer from those who disagree with “America First” proposals: Who are you rooting for?
Personally, I think he's casting his pearls before swine, but maybe this is how the conversation starts. There are some sensible people at Harvard, and at the Ivies in general. They are just a minority, and they're not usually the loud ones.