The Lord's anointed is not a respecter of persons. Love does not respect the flesh of people but honors the opportunities of life to express Christ. Elihu in Job 32:4-22, God's man, failed to see age as a factor in evaluating the worth in the words of counsel. But rather, "There is a spirit in a man: and the inspiration of the Almighty giveth him understanding."
God deliberately ordained Josiah, a young boy to be king of Judah, and he was God's man walking in the ways of the Lord. There is a wonderful revelation to us about the way of life through the Holy Spirit. God chooses whom He wills; the earthen vessel is not the issue, but the treasure is. God speaks from the mouths of babes and sucklings and has ordained strength that He might still the enemy and the avenger. Is it deliberate that Joseph, until the birth of Benjamin, was the youngest of his brethren? Is it also deliberate that David was the youngest of his brethren? After all, who made it through the wilderness? Was it the old and aged ones who had initially left Egypt and experienced the 40 years of trials? No, they never tasted of the wonderful Canaan land. The Holy Spirit ordained for the new generation, the younger ones, the babes and sucklings, to receive the blessing!
Is it a wonder that Jesus said unless we become like little children we will in no wise enter the Kingdom? Our fruitfulness in old age (Psalm 92:14) rests in our availability to the heart of the Holy Spirit.