AFAIK, owning an alligator ANYWHERE in the US is verboten, because it's wildlife, same as it's illegal to keep bears as pets. It' considered the property of the state. Up until 1987, alligators were on the endangered species list, and if you were caught with one, you'd serve some serious prison time. My brother knew somebody who had one in his apartment, and was over 2 feet long. You don't have to wait until they're 12 feet long before you start to worry. Alligators are alpha carnivores, top of the food chain. That means even when they're only 4 or five feet(that's about 5 years old), that alligator now considers you on the menu. The way the zoos deal with them is they keep them very, VERY well fed, which makes them sedentery.
Personally, I think anybody who keeps things like Alligators, Tigers, Bears, Poisonous snakes, etc inside their home, is more than a little nuts.