Not shooting the President and losing a fight with Firefly was the supposed Apparent Defeat that pushed the Joe's backs against the wall, hoping for one last shot to redeem themselves. Except their backs were ALWAYS against the wall and despite Lady Jaye saying, "Remember, this is your ONE shot.", it sure didn't feel like it was their only shot to expose him. (I mean, if an alley across the street was an isolated enough spot that the Secret Service would have never thought to cover, I think you probably could have ample opportunities to take a crack at the guy.) And, as you noted, there really wasn't a need for redemption.

After this and Gangster Squad, I'm starting to think that Zombieland was a fluke for both the writers and the director. You can blame the studio for a lot of things but I can't even imagine how this could have been a strong script to begin with.