You can read accounts here and here.  The University's explanation is transparently nonsensical, absent a showing that the Provost regularly overrides hiring decisions about adjuncts by departments even when rabidly Zionist politicans don't send in letters of complaint about the views of the instructor.  What an embarrassment for a College with a distinguished academic history to cave in to craven political censorship this way.  You may sign a petition in support of academic freedom at Brooklyn College here. 

UPDATE:   More information here.  Philosophers, please sign the petition too!