I'd say it is a generally accepted factoid, but not universally. Your own source begins thus: "Nationality is membership of a nation or sovereign state." The article then goes on to prove exceptions to the rule.
I'm not fervently attached to that concept of nationality equating to citizenship, but it seems to work in English-speaking countries.
My main point was that race and nationality are different things.
(Some people would also disagree with that.) There's too much political baggage tied up in these definitions for them to have a universal meaning.
I consider myself racially Caucasian: 1/2 Italian, 1/4 English, 1/4 Scottish. But my nationality is Australian. And the vast majority of Aboriginal Australians accept their nationality as Australian, even though some call their nation Pitjantjatjara or Yolngu, or some other tribal identity.