Because they've done their homework, and they know that McCain's advisers support world hegemony for the U.S., keeping wars on multiple fronts going indefinitely, attacking Iran and Syria and taking control of the oil in the Mideast, controlling space with weapons, and setting the U.S. up as dictator of the world. Some of McCain's advisers are affiliated with the PNAC, and its infamous RAD (one of the scariest documents since Mein Kampf). The Middle Eastern countries are afraid of McCain, because they know he wants to follow the Cheney plan of political globalization. They don't want to be victims, so Obama looks more reasonable to them.
The Council on Foreign Relations
political analyst Elliot D. Cohen
the PNAC's RAD