Al Qaeda always wants the world to know of the things they have done. Most terrorist groups do in fact. That is their main source of leverage. Since when are muzzie jihadis worried about getting killed?
As I stated earlier, they ran into the mountains of Afghanistan and hid after 911. No way they would not expect a major counter attack for an attack just 2 months before an election. Heck, every President running for reelection wants the perfect October surprise. And this one was handed to Obama on a silver platter. Why did he not take it ?