"PS. Nobody has yet responded to my comment that antisemitism applies to hating Arabs just as much as to hating Jews. "

This topic was covered at the Mudcat several years ago at other blame
Israel fests. As EmmaB correctly poits out the term anti-Semite (and its varions) was coined specifically and solely to apply to Jews, and is attributed to William Marr (spellings differ).

To claim not to be anti-Semitic because one does not have animus towards Palestineans or other Semites, is a misuse of the term. Continual and deliberate use of it incorrectly may, in itself, be proof of anti-Semitism by the user.