I can absolve Nagin for his actions after the hurricane, but I cannot absolve him for his failure to effectively use (or at least try to use) the evacuation plan.
The corrupt local school board never gave him permission to use school buses.
And the state had to approve any plan to evacuate anyone outside of NOLA.
He was effectively prevented from acting from below and above.
However, he should have screamed about this well before the hurricane was approaching and shamed the parties involved into acting.
But, then again, when it comes to Louisiana politics, there apparently is no sense of shame.