Might consider also that Argentina is small population wise on a continent that's mostly not white. People are clinging to their heritage and hopeful that they can keep it in the face of being swamped by other cultures. We hear a lot about what it's like to be a minority in the U.S. Spend time in Mexico and you get a sense of what that's like if you are white. Other ethnicities and races are celebrated in the U.S. and elsewhere but celebrating your own white heritage is seen as celebrating white supremacy which is disparaged. I celebrate my Cherokee heritage. Am proud of my Scots-Irish heritage too. And don't want anyone in my face telling me I should be ashamed of either. Shit happened and it happened everywhere and wasn't committed by just whites. Deal with it. The premise of the original post seems to suggest that claiming whiteness is wrong if you have some other DNA in you. Most Argentinians are descended from Europeans. This isn't complicated.
The article is not serious; if it were, they would look at the
percentage admixture among those with some African ancestry and from that they could get
overall admixture. But that would undermine their polemic and only a few nerds of anthropology, history, and genetics like myself would read it. The purpose of this UK propaganda outlet is to undermine the identity of Argentinians.
Genetic Ancestry
You could show through genetic analysis that the Turkish are not really Turks. There are large components of Kurdish, Arabic, Greek, and Slavic admixture. But of course the Guardian would not do that.
You could challenge the identity of Guatemalans as a Mayan people by showing the large Spanish admixture.
You could say the Haitians are not really and African people because of French admixture.
You could say the Aboriginals of Australia have gone extinct because it’s so difficult to find a pure one and the ones remaining are not true Aboriginal Australians.
You could do this for virtually every ethnic group on earth and you would be correct. But a nation’s identity is idealized and mythologized. It's an important part of the human experience.
Heritage Pride
Then you have those that may grant that Argentina ancestry and culture is largely derivative of Spanish/Italian heritage, but that they shouldn’t be too proud about it. Well, every healthy nation is proud of their heritage to varying degrees, and Argentina hardly oversteps normal bounds.
The Chinese consider China to be the Middle Kingdom; the center of the earth, everything revolves around them.
The Jewish say they are God’s Chosen People.
The French say nobody else knows how to dress, eat, and speak except them.
Again, we could go on for virtually every ethnic group. Virtually every nation, tribe throughout history positions themselves centrally and differentiates between “us” and the “rest.”
The Guardian's article is an attack on Argentina’s identity and is part of the broader anti-European campaign you see in much of the Western world as you have identified. Though these kinds of attacks are also mounting against non-European peoples such as the Japanese. The primary force behind it is probably global capitalism, which pushes for unrestricted movement of capital and labor. Other resentful and opportunistic groups/people join; you can call these the useful idiots of globalcap.
Having lived in many countries, such as India and Singapore, I’ve discovered that a substantial proportion of expats hate the country they have migrated to. You will find a disproportionate number of them in online forums. Curiously, they don’t leave. Some may have put down ties that make it difficult to do so, but I think the better explanation is that they are deeply unhappy people that were unable to find fulfillment in their own country; that probably had something to do with their decision to relocate; they carry their toxic psychological traits to the new country. Unable to assign fault to themselves, they blame their new home, never feel at home, but neither can they go home. We can only hope these unhappy people, these lost souls, someday find peace.