"so that that well-defined term is turned against Jews" - but anti-semitism is an anti-Jewish term in the first place, taken up for that very purpose, by pseudo-scientists in the 19th century using an irrelevant linguistic categorisation.

"Wilhelm Marr coined the related German word Antisemitismus in his book 'The Way to Victory of Germanicism over Judaism' in 1879. Marr used the phrase to mean Jew-hatred or Judenhass, and he used the new word antisemitism to make hatred of the Jews seem rational and sanctioned by scientific knowledge."

I cannot see how using the term in a broader sense is "the quintessence of anti-Semitism." Whether used in a narrow sense or a broad sense it is a vile thing which should always be resisted.

Would anyone claim that opposition to anti-black racism was somehow diluted or challenged if the term "black" was interpreted to include people who are brown?