It has been proposed that Moore didn't use the typical leftist "zionist - Israeli lobby" because he wants to defeat Bush and this might turn off some jewish voters, who tend to turnout heavily in support of dems. It's just speculation.
Then again, if Moore had played up the antiSemitism angle, it would have drawn even more comparisions to Nazi documentaries like Triumph Of The Will and The Enternal Jew. It also would have been harder to separate these conspiracy theories from Democrat also-ran Lyndon LaRouche.