It’s quite obvious that none of the people in that thread (bar maybe the one guy who lived in Spain and knows how idiotic the belief that they are “mixed” and somehow different from other Europeans is) have any real grasp of the topic they are talking about, at all, in any way.
There’s an extremely good reason for why the only places where those 19th century-style debates about whether some major groups of Europeans are “mongrels”, or “invaders”, are taking place, are obscure racist, segregationist, white nationalist/supremacist and other crackpot websites like the one this quote is from, with any mainstream scientific interest in the issue having been dead for decades. That reason is a little something called genetics. Study after study has repeatedly shown that, barring very few genetic isolates (Basques, Sardinians, Icelanders, Finns and other peoples from the extreme North-East of Europe (Samis and Komis)), Europeans are extremely genetically homogenuous, with continent-wide samples showing genetic diversity comparable to single population samples from elsewhere in the world, genes mirroring geography and seamlessly flowing from one population into the other, with there being pretty much no real way to divide the vast majority of Europeans into discrete populations on a genetic basis.
Here’s an image from the linked Wikipedia article which illustrates this: image
From Spain to Russia, and from Italy to Sweden, all European populations are tightly clustered together genetically into a single mass, with the two outlier populations, Estonians and (especially) Finns, together showing a similar amount of genetic diversity as all the other populations put together.
Also, since OP is talking specifically about the Spanish and the Ashkenazis, I’d point out that that article also has this comparison of genetic distances between various European and non-European populations. Despite hundreds of years of intermarriage, between both Ashkenazis and Europeans in general, and Ashkenazis and Spaniards in particular, the latter are still genetically closer to the Swedes, the archetypal Europeans according to the OP’s lot, than they are to the former. Only the Russians, a population on the opposite end of Europe, are genetically more distant from them than the Ashkenazis.
Seriously, the sheer amount of American far-righters who just automatically associate speaking Spanish or Portuguese with not being European, and then start speaking utterly deluded bullshit about distant countries they’ve never been to, is just maddening. The amount of times I’ve had some serious second-hand embarrassment while reading American far-righters talking about Southern or, less commonly now, Eastern Europe, is just stupidly large.