Is it this recipe? recipes.sparkpeople.com/recipe-detail.asp?
I haven't made this myself but I've done similar things in the slow cooker. Corn is pretty durable, and if you include it in the slow cooker directly from a bag of frozen corn, I don't think it would get mushy. Or, you could cook a little bit & sprinkle it on when you serve it. Or the person who made the recipe is using a salsa with corn in it. Or they accidentally forgot to include it in the recipe. I've done things like that before.