While I don't know of any peer-reviewed studies on this, I can say that you are correct. Unfortunately, I know this because I have made this mistake myself. I used a product called a "10 Frame Insulating Foam Board" one year. In the product description, they recommended placing the board between the inner cover and the outer cover. However, my inner covers have cut-outs, and the bees still managed to chew the foam board above the cut-outs. I definitely think it's a good idea to use foil surface insulation or foil tape to keep bees from chewing the foam!