The illogic of "English: The vanishing language"

The current wave of anti-immigrant hatred is filled with images of violent threats to our society -- Pat Buchanan's State of Emergency argues literally that Spanish-speaking immigrants are out to "conquer" large parts of the US. Of course the 'threat' to English in the US plays a central role in this. Michael Reagan not long ago published a piece in Human Events railing about this threat to English, with the title given in the subject line. (I cannot bring myself to link to that journal, but you can find it easily enough.)

Let's leave aside the truly bizarre conclusion Reagan reaches, that "the English language is on its death bed", due to immigrants and their "enablers", and leave aside his propagandistic use of language ("hordes" who "chatter" in their languages, and so on). And when he writes about the "age-old custom of immigrants to our shores who made it one of their first priorities to learn to speak English and to teach their offspring to do likewise", he could be ignorant of the broad and consistent patterns of evidence showing that earlier immigrants learned English much slower than today's -- in the Upper Midwest, some third generation Germans remained German monolingual; are there today many young people in this country whose grandparents came from Mexico who can't speak English?

But only someone who is consciously engaging in misleading people would draw his many alarming conclusions from raw numbers of immigrants (why should we be alarmed that one in five people in the DC area is an immigrant?) and of people who use a language other than English at home. He leaps from Census numbers on this to declare that people "refuse" to learn English, feel that they don't need to, and "don't intend to". Nothing in the numbers he cites could possibly provide evidence on those points.