I don't see anything wrong with fining people who refused to leave, as long as it could be proven that they had the ability to leave and chose not to. Of course, the Mayor and Governor should be fined as well for not enforcing the mandatory evacuation order and busing those that could not leave the city either.
Why the hell should people be fined for making and independent choice using free will? If those people are stupid enough to want to stay and risk their lives that's absolutely their right to do so w/out fear of penalty or prison sentence. The same can apply to helmet laws and seatbelt laws.