This is an interesting list. What criteria did you use to deem a plant safe for chickens? Where are you looking when you are researching?
I am surprised that you don't have many fruit trees on the list (other than citrus). I am kind of surprised that citrus made the list because I have seen citrus on the not good/safe to feed chickens. (However, in my experience, they don't bother to eat it anyway).
I love that you put the disclaimer on the article that just because the plant is safe for chickens, doesn't mean the plant is safe FROM chickens!!