The determinant of a hero is whether or not they benefited mankind with their actions. Let's be frank here, Bin Laden didn't do shit for anyone.
And for the record, Bush and Genghis aren't really considered heroes. Genghis was a great //leader//, but not in a heroic way lol. And Bush...well...he is the result of Osama's poor judgment, along with 9 years of fruitless war.