Thanks for playing! He's got a big stomach, so you might need to feed him a lot to fill it. Or, you could try mixing something into his food to make him need to leave...
I found out that you must include the word "rotten" when mixing the food with the meal even though you do not need to include the word "rotten" if you just examine the food, e.g. X FOOD works fine. It would be good to make the word "rotten" optional when mixing the food with the meal.