Even if he was, it’s not obvious that the actually existing acculturation people do to participate in the global cultural middle class is entirely composed of culturally universal middle-class traits, rather than accidental traits attributable to the particular areas where this culture emerged first.

Some such traits undoubtedly exist; for instance, people throughout the world learn English for no other reason than to take part in a successful culture where "middle class" traits are relatively common. But it's not clear that there could be any alternative to English that would not be "attributable to [some] particular area"; for example, Esperanto is culturally European and perhaps even specifically Eastern-European; Lojban was indeed designed to be culturally and areally neutral but this doesn't seem to help its popularity, since the Lojban-speaking community is in fact quite tiny.