The definition and abbreviation for Potentially Hazardous Food (Time/Temperature Control for Safety Food) or PHF/TCS should be modified to drop the reference to potentially hazardous food and PHF.
Yes, as a treat apples are fine for chickens. Some will say it is best not to feed them too many apples as the seed of an apple has a small amount of arsenic in it. I have an orchard on my property and in the fall, the chickens run there first thing in the morning. Never had a chicken drop dead under an apple tree.
If you do feed nuts or seeds to your ducks, they should be ground first. Apple and cherry seeds are toxic so avoid those all together, as are peach and apricot pits. For a more complete list of toxic treats for chickens and ducks read HERE.