I think what he’s saying is anti semitism is a mirror of Jewish identity itself. “Jews are special, we are a special people with a special destiny” is mirrored but the anti semite saying “yes but specially bad!”
SCB seems to be arguing Jewish identity itself isn’t real-it’s a constructed identity like any other. The ultra orthodox rabbi that believes in a trans historical Jewishness that exists for all time and has no specific historical dimensions or peculiarities is copied by the anti semite who agrees but instead of seeing the God chosen nation of priests, sees a uniquely malevolent creature that exists apart from all others.
I’m probably being too charitable but the gist of his argument is anti semitism replicates the same assumptions and prejudices officially sanctioned Jewish identity is built on “we are different we are special” “the Goyim are godless, heathen, stupid and we have to bring them the light” “Jews are uniquely malevolent, cunning and egotistical, and see other groups as I stupid, servile and deserving rulership”.
TLDR: Anti semites simply take Jewish identity claims and reverse their value judgements.