In understanding Joseph's bizarre behavior, it helps to remember that the ten brothers were not seeking a reconciliation with Joseph.
Standing before the ruler of Egypt, Joseph's ten brothers were surprised when he asked diligently about their father and their brother. Later, the ruler would have them seated correctly according to their ages. How could they not even suspect that the ruler was their brother?
Psalm 119:74 tells us: "Those who fear You will be glad when they see me, Because I have hoped in Your word."
Christians who are hateful to other Christians don't fear the Lord, and none of Joseph's ten brothers feared the Lord. The Bible abounds in blessings for those who fear the Lord, and recognizing that none of these blessings applied to his brothers might have influenced Joseph's own behavior.