Why use 2 types of flour in this Hooters Hot Wings copycat recipe?

This recipe is dusting the wings, so the structure of the coating is formed from starch in the flour. There is little gluten formation.

In this case, one of the two flours is whole wheat flour, which would be very non-traditional in a deep-fry coating. I can only conclude that the recipe author desires the whole wheat flavor, or that they feel there is some nutritional or other benefit to using whole wheat flour.

It would be far more normal to use 100% all purpose flour, and that is likely to work in the recipe just as well, if not better. For example, Food.com has a similar imitation recipe which uses only regular flour.

The reverse, 100% whole wheat flour might work, but would have even more whole wheat flavor. There is some risk that the bran in the whole wheat flour will also add a strange texture to the coating, but I suspect this is less likely to be a contributing factor. I infer that the recipe author balanced the ratio to his or her taste.

In the end, I would go with a traditional recipe that uses only regular flour if I wanted a coated wing, but that is just me.