From the article:
It is a moral idiot who thinks that anti-Semitism is a threat only to Jews. The history of civilization demonstrates something rather different: Judaeophobia is an unfailing prognosis of barbarism and collapse, and the states and movements that promulgate it are doomed to suicide as well as homicide, as was demonstrated by Catholic Spain as well as Nazi Germany.

In the light the famous poem by German anti-fascist Martin Niemoller:

("First they came for the Communists, but I was not a Communist so I did not speak out.
Then they came for the Socialists and the Trade Unionists, but I was neither, so I did not speak out.
Then they came for the Jews, but I was not a Jew so I did not speak out.
And when they came for me, there was no one left to speak out for me.")

... I am inclined to agree with the first sentence of that piece.

But it's rather presumptuous, arrogant to assume only anti-semitism is a sign of barbarism.
Furthermore, I'm not sure that the fourth 6 million will be thrilled to have been Hitlers ultimate poison pill? If that IS the reason for his demise.
Also, Catholic Spain? The inquisition killed indiscriminately jews, arabs and protestants, so I'm also unsure how exactly then the poison pill effect worked on Catholic Spain, rather than just France or whoever bucking for power.