You are wrong. 100,000 people couldn't leave. Even a bunch of tourists were stuck - you think they wanted to be staying there? It wasn't about heeding warnings - it was about failing to adequately plan.
Nobody was stuck. Tourists could have gotten cars to leave, could have gotten a plane before the airport closed, could have gone into the superdome. If they had legs and a brain then they could have walked from the Quarter to the dome.