The assumption that the Arab/Muslim leaders would care about Western opinion enough to spare the Jews is projection. The concept of world opinion is a construction of late 20th century media. Information did not travel that fast. Furthermore it projects late 20th century/early 21st century Western cultural attitudes towards treatment of prisoners, minorities, and genocide onto a group with significantly different attitudes. It was not that long ago from 1948 that we had the Armenian genocide, Turkmen genocides and the Farhud with nary a critique from contemporary Arab sources ( at least none that I can find). Given the indigenous contempt for dhimmi Jews paired with imported Nazi and Czarist Jew hatred why is it so hard to imagine that the Arab leadership would not balk at slaughtering the Jews again. They hired ex- Nazis as officers and Pasha Glubb. Not exactly the kind of people who will be merciful to the Jews. Given the US state departments dismay at Truman's decision to recognize the Israelis, I can imagine many would look the other way with an I told you so thrown in during a massacre. The British FO already hated the Zionists so no succor there. And Stalin the less said the better.