This is close to my heart as I was in this hotel just over a week ago.
I do not believe Disney failed in their duty of care. We sat out every evening by this very beach. There is signage every few metres that says no swimming - this beach is also about 20 metres from a very child friendly pool.
We saw quite a few toddlers paddling in the water. The water is pitch black as its run off from the pine forests , so its neither attractive, nor if you believe the signage safe. Do not for one moment think this is a clear blue water lake . I was brought up by the sea and have a built in respect for water.
If it says no swimming there is a reason.
There are many, many other places ( complete with sand) and lifeguards where these parents COULD have taken their child. Instead they disregarded the signage and common sense and paid a price I can't begin to imagine.
This IS Florida, alligators are native wildlife. In my 30 + years of going to Disney I have only once seen an alligator, about 3 foot long in a water run off, not accessible by people. However, common-sense tells me that spiders, alligators and even such things as squirrels can injure and you should be on alert.
So whilst my heart breaks for these parents and the loss of their child , short of erecting a 6 ft fence ( and we all know how effective that is when faced with curious toddlers - thinking on the recent fall into the gorilla pit)or putting in a shark type net several metres out in the water, what more could Disney have done?
Nonnie Disney has no performing animals outside of the Animal Kingdom which is a safari style park where the animals live in 'natural' extensive habitats. You're thinking of the Orca at SeaWorld. Not a Disney owned park.