Well... try this on for size then: 9/11 *was* a victory for the terrorists. They won the day. They brought down the World Trade Center and took out a huge section of the Pentagon. As missions go, it was a raging success for them.
Just as Pearl Harbor was a victory for the Japanese Navy.
Should the film have denied this? Of course not.
What Flight 93 represents however is the first return of fire. The first response to their attack. The first people to fully understand the nature of the day made a courageous decision to fight back. If this doesn't capture the basic true American spirit, in the face of evil, I don't know what does.
It's a story that needs to be told, and it was done just right in this film.
Then why didn't they show the vote?
Because the director needed to retain the balance between the terrorists and the passengers. Showing Americans voting and making decisions while being terrorized would favor us - and make the terrorists look evil. It would not sell overseas.