Another long-time reader that this case has made into a first-time poster.
I'm familiar with the kind of terrain in Carlton Reserve. Camping in swampy subtropical conditions is never fun, but this time of year it is close to hell on earth. As others have said, the mosquitoes and flies are thick and relentless, there is no way to get dry or stay dry, the heat is dreadful, there is no water that is safe to drink, there is just about nothing that can be foraged for food, and the gators are a serious concern, especially at night. I don't think Brian is in Carlton Reserve, and I doubt if he was ever really back in Florida. IMO.
For a good look at what these conditions are like you can search Les Stroud Survivorman Georgia on Youtube. There's an episode of Survivorman (featuring Les Stroud, who is a well-known and highly-skilled primitive survivalist who has been dropped into harsh conditions all over the world to film himself contending with nature to stay alive) set in a swamp that is very similar to Carlton Reserve. It shows how hellish the conditions are; Stroud himself says that after thirty years of doing minimalist survival camping, that swamp was hands down the worst conditions he ever endured.
Based on their car-camping itinerary and on his behavior, Brian is far from a Les Stroud; he comes off as a poser who seems to have little or no real back-country knowledge, IMO. He wouldn't have lasted more than a day or so in Carlton Reserve on his own. I don't think he's in there.