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.
Two extras that you need to know about when feeding your chickens are calcium and grit. Chickens need calcium so they can produce healthy shells for their eggs, and they need grit to help them break down their food since they don't have teeth. Though tempting, do not feed egg shells back to your chickens for calcium. Chickens are more likely to start pecking at their own eggs if you do this.