As I have tried to wrestle of the legal ramifications of this in my head, I tend to believe Disney has an uphill battle as there are several points that will be used against them.
1) There is no right answer to the sure to be requested answer to, "How many gators do you pull out of the Seven Seas Lagoon?" - If they say 2, they will be blasted for being negligent in trying to resolve the problem (i.e. they put profits over this boy's life). If they say 1,000, they will be blasted on why do they have an entertainment area so close to such a dangerous area. There is no correct answer for Disney and it will all look bad.
2) Disney encourages people to be on the beach at night. - There is no denying that Disney considers the beach a night time entertainment area.
3) The beach is poorly lit. - Since most of the night time activities (fireworks, water pageant) thrive in lower lights, it makes sense that Disney would not focus on extreme lighting on the beach.
4) Wading versus Swimming - Even the police officer made the distinction of them being different. While you could say that common sense should have dictated an assumption of danger, that won't hold up well in court.
5) Not a Local Family - I am guessing there are no alligators in the State of Nebraska. Regardless on there true knowledge, the prosecution can always present that the nature of alligators just was not known to the victims.
There was a great picture earlier in this post that sent shivers down my spine of a little girl playing by herself with her back turned to the shore playing near murky water with a very generic no-swimming sign. That picture was the nail in the coffin for me. It sent shivers down my spine. There was no denying that the girl was happily having fun in an entertainment area with no real fear or knowledge of what dangers could be lurking a few feat offshore. It was exactly what Disney wanted. Unfortunately an astronomically improbably event occurred that resulted in a horrific tragedy. Due to the violent nature of the event it repaints that entire picture as eerily dangerous. There is no way that a parent or Disney really would believe this type of event was going to occur. From a legal standpoint this is going to come down to Disney is responsible for ensuring that entertainment areas are safe. They should have been looking out for the guest and anticipating this tragedy. Legally this will be...Disney encourages families from all over the world to entertain at night in a poorly lit entertainment area a few feet from a lake they know contains lethal predators without adequately warning the guests of the dangers they are subjected to by being in that area.