No doubt this sort of thing is going to play out again and again wherever those "choice cuts" from the SuperDome evacuation end up.
Friend, if I were you, I wouldn't have anybody stay at my house, period.
If they're being adequately cared for by your local municipality, they should thank their lucky stars, be grateful for whatever they're given, and remain content with that provisional arrangement.
I live 40 mi. east of Austin, TX, and I'll be damned if I open my home (and expose my family and neighborhood) to the threat of harm at the hands of strangers like these.
If folks think that's being hard-hearted, so be it.