Coffee in a rattlesnake recipe? Why? WARNING - IF YOU HAVE A PET SNAKE LOOK AWAY NOW!

The quest continues!  The back story to this question is:  My friend is competing in a competition, the main ingredient should be lizard, however I pointed out to her that some people didn't like talking about lizard.  I suggested snake, yes, she can cook snake, and be judged on that, as there will be other snake dishes being offered.  

Now, I've eaten snake, and found it quite palatable, but I have never personally cooked one.  

I asked what equipment they will have access to: BBQ grill, oven, broiler, hot plate for pans. I asked if there were any other requirements as per the ingredients - no she can use what ever she like.

I found this recipe for fried rattlesnake with ham gravy particularly interesting, but am struggling with the coffee bit in it.  Not quite sure why it calls for that, and to my mind sounds wrong - so the question is:  what can she substitute for coffee in this recipe and what does the coffee achieve?
It's not a mistake. It's there because people like the taste of coffee in meat dishes. It adds some richness to the flavor, definitely something that works well with meat, and I doubt rattlesnake is any exception. I've had chili with coffee in it, and plenty of barbecue rubs with coffee. (I don't remember a specific recipe I've had, but for example these ribs look good.) You can find recipes for all sorts of other things, e.g. beef roast with coffee, pork tenderloin with coffee, or coffee beef jerky. You'll see dark chocolate or cocoa powder used in a lot of similar ways.

Unless you have a coffee allergy or can't get coffee, I'd try the recipe as written before you write it off. You could use instant if it's just that brewing real coffee is a pain. If you really can't use coffee, I'd try cocoa powder and water, in a ratio like hot chocolate, minus the sugar. You could also substitute milk or water or stock or any appealing liquid if you don't want to use coffee, I suppose. You'd still get a gravy, just not the same gravy, not the one the recipe author intended. 

And of course, I'd give the same answer about any meat recipe with coffee in it, not just this specific snake recipe. It might be surprising if you haven't seen it before, and I guess it might not be as common outside southern US cuisine, but it's a good idea.