"From the simulation, officials estimate that a storm like Hurricane Pam would... cause flooding that would leave 300,000 people trapped in New Orleans, many of whom would not have private transportation for evacuation...."
Brown is a very inattentive man, it seems. His agency finds that an evacuation of the city is apt to leave 300,000 citizens behind, but when a real disaster strikes and many citizens are left behind when the city is evacuated, he is surprised. This guy has to be one of the all-time champion bureaucratic bunglers. That he has joined the chorus of those who are passing the buck to the victims makes him one of the most repugnant, as well.