This sounds like straight up Nazi propaganda. The idea that races are so different that we literally inhabit separate realities is insane levels of bigotry.
“History is written by the victors” is a famous phrase a reason — facts are a representation of the information we are most confident in, not truth.
Anyway, critique of that quote aside, how's it relevant to Wikipedia?
To say that Wikipedia is not representative of its editors, is to say that history is not representative of the victors.
To pick an example of a group that is somewhat insular: if the majority of Wikipedia editors were Chinese, would Wikipedia look as it does today? Would Wikipedia be an equally-as-accurate reflection on the west as Wikipedia is today?
There's a Chinese Wikipedia site: https://en.wikipedia.org/wiki/Chinese_Wikipedia
However, even the English-Wikipedia's articles on China are likely to be disproportionately influenced by Chinese posters, even if they're a minority of the overall contribution-base.
That said, what's the potential relevance here? Is this purely about articles on politics, or..?
There's nothing intellectually controversial about Wikipedia's statement, to argue against it on the basis that it's impossible to parse seems anti-intellectual rather than... actually challenging the content of the statement.
You may wish to argue that Wikipedia can simultaneously be an encyclopaedia that represents the world AND be an encyclopaedia mostly written by middle class white people, but that's a point that requires much more discussion than a hand-wavey statement about how this discussion isn't relevant to your friends and family.