I could not agree more. Working class students tend to use education as opportunity to learn the dominant discourse and thus a chance for upward mobility. Liberal elites, on the other hand, view it more as pursuit of their intellectual interests. Thus, you see traditionally underprivileged students flocking to business and engineering departments, while white middle cass students pursuing liberal arts. The same pertains to languages.
My other guess is that bilingual education may be favoured by elite liberals who tend to see culture as more important than material living conditions, as well as 'ethnic studies' majors who have few job opportunities other than bilingual ed. My son, who grew up in the US had little desire to learn the native tongue of his parents, and it was mainly my wife who insisted that he learns it anyway (she still gets pissed off when I talk to him in English, for practical reasons, since his command of the Polish is rather limited). As far as I can tell, a similar situation exists in many immigrant families.
On the other hand, neither my wife not I would even for a moment consider sending our son to an 'ethnic' or bilingual school - we both agree that this was a dead-end road.