No, it's that the vast majority of immigrants are not working in tech. The vast majority of Americans are not working in tech. We have something like 11 million undocumented immigrants: their staying in the US should not be contingent on them being a part of the new business scene.
Furthermore, why should the US be encouraging technologists to immigrate here, when fundamentally those immigrants are in the business of putting other people (Americans and immigrants both) out of work? Yes, this is great for Silicon Valley, and probably is good for NYC, but what about for Iowa and Nebraska?