Hullin 142: The Reward of Long Life in the World-to-Come

A new mishnah! The last one, to be sure. Taking the mother bird for the fledglings or eggs -- you take the mother bird for the sake of the purification of the person recovering from tzara'at. Meaning, the mitzvah of that purification doesn't make it permitted to take the bird under the circumstances of her being on her chicks/eggs. Also, the philosophical conundrum of one who sends away the mother bird, for which long life is promised, and at the behest of his father, so honoring his parent, for which long life is promised, and then dies on the descent. How to reconcile or resolve this contradiction? [Who's Who: Elisha ben Avuya, aka "Aher"]