Then they should say white. I'm prepared to give a lot of leeway when conversing with non-native speakers but as somebody who has grown up within a culture that understands that the concept of cultural homogeneity cannot refer to native speakers of non-mutually-comprehensible languages or historically antithetical religious positions, if they choose to use the word in novel ways that's their problem not mine!
I don't know what the exact word is - I wouldn't quite say "culture", as there are clearly different cultural backgrounds at work, but just as with Canada mixing French and Anglo traditions, there is a generally homogenous Western European metaculture at work, premised on the Enlightenment, classical liberalism, the rule of law (and equality of opportunity under the law), freedom of religion, the importance of education and hard work, private property, and personal responsibility.
Ah, a generally homogenous Western European metaculture then, like that Canada! Thanks for engaging with the specifics of the Swiss Enlightenment you can keep the change