That is not a fair statement of what he said - you assume that the culture has not had a long time to preserve its cultural knowledge and that a dying culture p

That is not a fair statement of what he said - you assume that the culture has not had a long time to preserve its cultural knowledge and that a dying culture produces much (after all it is dying for a reason) and you assume that the person can only speak the dying language. And even then everybody would try convince that person to translate his culture into the new language or at least to codify the original language so that it isn't lost. But the real solution would have to start doing those things decades ago.