[derrida]

How exactly were the Left involved with the approval, under Menachem Begin, of Yassin's application to start the "humanitarian" organization Mujama?

You mention the Islamic University of Gaza, which was Islamicized only after an administrative coup, aided by Israeli authorities, who then tacitly permitted its use as a training grounds and armory for suicide bombers and anti-secular thugs. It's inaccurate to say that the radical muslim brotherhood enjoyed widespread support at this point in time.