I don't know if we are still discussing the original topic (it's hard to tell around here sometimes) but after giving this thought, here's my opinion (which might prove to be vastly unpopular, but like that's never happened before!)
I live in New York City. On September 11th, almost 3000 of my neighbors were killed, through no action of their own. They weren't fighting a battle, they were on their way to work. They were killed because they were Americans. Today, many of the First Responders -- the people who spent their time in the ruins of the WTC trying to find survivors, are dying of respiratory illnesses directly caused by the particles from those buildings. Not to mention the psychological pain of all of the families and friends of all of the people listed above.
So, if we want to celebrate the assissination of the evil son-of-a-(can't use word on the Dis) who was directly responsible for all of that pain, we will. And we really don't give two doodies if anyone is condemning us.