Moreover, foreign mindsets are durable over generations: https://www.sup.org/books/economics-and-finance/culture-tran... ("In The Culture Transplant, Garett Jones documents the cultural foundations of cross-country income differences, showing that immigrants import cultural attitudes from their homelands—toward saving, toward trust, and toward the role of government—that persist for decades, and likely for centuries, in their new national homes. Full assimilation in a generation or two, Jones reports, is a myth.").
Right, and most countries are very conservative compared to the US, in particular many of the countries that the average H1B holder is from. India, for example. That means Republican voters. The entire premise is flawed fearmongering.