I've been on a swamp tour in Louisiana, but I still wouldn't want to let any cat get that close to an alligator! Still, maybe the cat knew what it was doing...
That's why I mentioned I visited Louisiana and went on the swamp tour. We also spent the night in a cabin in the swamp and had a day tour with our Cajun host in the morning, and saw all of the alligators they raise in their backyard. I know the Florida ones have a record of being quite lethal, but the ones we saw (and fed), just seemed and behaved like very big lizards.
Perhaps it was a feral cat and knows what an alligator is, and I dont think your allowed to get out on a Tour near a wild alligator or you risk getting attacked yourself!