Symbolism, Imagery, Allegory
This alligator is dead.
In order to lure tourists into paying for a boat ride though, Sickler promised that they'd see a gator. To make good on his promise, he nailed a stuffed gator to a log in the middle of the swap to trick tourists into thinking they were seeing the real thing (10.82). He did it for money, of course. Well, Old Sleepy is a symbol of the use (and abuse) of nature for human profit. Nature that is used for human profit is often called a natural resource, like wood from trees, concrete from rocks, and gasoline from petroleum.
Old Sleepy is just a smaller version of what reality TV is: a way to manipulate people and exploit nature. You might be thinking that Mickey uses animals for profit, too, and you'd be right. Kind of. The key different is that Mickey uses the money he makes from wrangling animals to take care of them, which makes what he does stewardship instead of just an attempt to make money. Mickey loves the animals he keeps, whereas Derek uses (and murders) animals for his own personal wealth and fame. Sickler's goals are more similar to Derek's in this way, and Old Sleepy reminds us of that.