A tragic case to be sure, however it is well known that Florida has alligators. Alligators will go wherever they please. They are opportunistic hunters. Stealthy. I am not familiar with alligators so anywhere alligators might be I give them a very wide berth.
There is no way I would dip so much as a big toe into a freshwater body of water at night, let alone allow my child to get anywhere near it. What little I know, I do know that gators are very fast on the attack for short bursts.
As a former snorkel tour operator I was frequently asked if sharks would be seen? My standard answer was that snorkeling is done in the ocean. Sharks are in the ocean. They swim wherever they please. 18 years. Never a shark sighting where I took people but there was always the chance.