i know i'm about to ruin the joke, but… to be fair, the 911 attacks and the bombing of Hiroshima and Nagasaki are a bit too different to equate to one another.
first of all, the Twin Towers were civilian targets, brought down during a time of peace. no one in that building was prepared to die that day. Nagasaki and Hiroshima, however, were military staging centers destroyed to end a war. the United States told Japan before the attack that if surrender was not given, they would be bombed. when choosing potential targets, the military specifically picked industrial centers with relatively low civilian populations, in order to maximize the hit to Japan's war effort while leaving major cultural centers untouched.
not to mention, it would have been far worse if the United States hadn't deployed the atomic bombs, and had instead gone through with their Plan B, Operation Downfall. paradoxically, the atomic bomb actually managed to save potentially millions of lives, both on the sides of the Allies and Japan, by forcing an early end to the Pacific War.

I wouldn't relate the two…