Let me first say that I am in no way trivializing what happened on September 11th. 3,000 people died and two of the longest wars in our history has been waged. Islamic Extreme Terrorism is the Communism of our day.
Disagree, they're worse. Communists had an ideology rooted in reality at least.
To address your point more fully, I agree DS9 was too ahead of its time, although I don't get much of a post-9/11 vibe from it. I definitely think if DS9 was made soon after 9/11 they'd be less willing to have a religious fanatic terrorist like Kira as one of the main characters.