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.
Don't feed your chickens citrus fruits, salty foods, rhubarb, chocolate, onions, garlic, grass or lawn-mower clippings, avocado and avocado skins or pits, uncooked beans, sugar, candy, and potatoes. Never feed eggs to your chickens because the chickens might develop an egg-eating habit.