Ok let me make this real simple for you as well and give you my opinion as to what happened to the "unity".
We were attacked by terrorists and those who support terrorists. Some of us want terrorists and their supporters to pay for this act and we will to do whatever it takes to prevent this from happening again. And to show that these people did not die without showing us of what we had to lose and that others are out to destroy it. Others feel the same but lack the backbone to go the extra mile to get the job done to protect what we have. That's where the short attention span comes in and where the "unity" runs out of steam. I don't need to have my country get attacked again to stay focused on what needs to be done.
So if someone says they and whomever are gonna do something to my family I don't need to wait for them to do it before I take steps to prevent it from happening. Especially if it I had let my gaurd down before and my family were the victims of my ignoring the threat.
I know your opinion. I just happen to disagree with it. See that's what Americans do. They sit around and pick on each other until someone sticks their nose in and trys to take advantage of it. So as much as we agree to disagree let no one be confused that if someone had you down I would be there to throw down with ya and I suspect vice versa. That's what the terrorists cannot understand. So our differences and ability to voice our opinions does build a bond, however invisible it may seem.