The legal interpretation will come, and be argued.
To me, it's a very practical topic, with very practical consequences.
The US through its history has grown its population into its land mass by being welcoming to immigrants. At some point, all immigrants (meaning, nearly all of our ancestors) were the "other," or unwanted. So, they came here. We ignore this history at our peril.
In current times, all industrialized nations, including China, are seeing their birth rates fall below replacement level. This is going to eventually show up in a number of factors: unsustainable pension and health care costs, declining real estate prices, increasing labor costs and inflation, reduced cultural relevance, etc.
In the long run, whichever advanced economy opens up to immigration, when the others are against it, is going to win. What "win" means depends on the country: economically thrive, dominate militarily, whatever. There will be a cost to this: immigration changes culture. It seems that what underlies most resistance to immigration is a fear of this change in culture, however it is packaged.
As a personal note: I invest in individual stocks. Successfully. Part of doing that is understanding you need to bet against the crowd at times; usually, when the crowd is loudest. The "move rightward" of so many societies, not just the US and Europe, but China, too, is quite a crowd, all yelling similar things.
