Like most seasoned conductors, Zubin Mehta has built his reputation on interpretations of a core repertory, in his case the music of Romantic-era giants like Bruckner, Tchaikovsky and Mahler. But on tour with the Israel Philharmonic Orchestra, an ensemble that named him music director for life in 1981, he is increasingly in demand for his exegesis of a long-winded drama fueled by high passions of a different kind: Middle East politics.