The minimum hot holding temperature for baked potatoes and other food is 135 F when set out and if the minimum holding temperature of the baked potato or other food in a food establishment is less than 135 F in temperature then the food or baked potato must be discarded and not served to the customers.
Now if you're at home letting a baked potato sit out and cool down below 135 F is perfectly fine and in reality it's safe but for food establishments who serve food to the public they must adhere to strict guidelines.
So if you're working in a food establishment and cooking baked potatoes then it must hold the temperature of 135 F or above when being served to a customer.
But usually you'll serve the baked potato much sooner than 4 hours unless you cook the baked potatoes way ahead of time.