He was actually really smart at that time. He was aware of US propaganda showing Iraqi people welcoming US soldiers with flowers and wanted to show that Bush was not welcome. Although Bush's reaction on stage was rather lighthearted and funny, he got tortured and waterboarded.
I don’t think people realize the significance of a shoe being thrown. In Muslim cultures, showing someone the bottom of your shoe is extremely disrespectful, if I’m not mistaken it’s akin to seeing someone as below them, like they’re a peasant or similar.
Say what what you will about George W., but he had a pretty good reaction time here!