A step too far?

This is where the story is in conflict with itself. Writers discount most of the content of the Gospels but then seize on the flight to Egypt as accurate reporting of a real event.

Herod the great in his last years was paranoid about almost anything. However the flight into Egypt is mentioned in only in one gospel, that of Mathew. none of the other gospels mention it neither does Josephus the other reporter of the period in question.

Nevertheless even Mathews mention of it demands some explanation. Why would the Holy family flee to Egypt?

The theory maintains it was to facilitate Jesus investiture as Pharaoh. there is a major problem with this theory as the inheritance in Egypt was Matrilineal. Only when the female inheritor chose her partner did the male Pharaoh achieve his status

“Because of the need to ensure that the next king was born to a woman of the purest royal blood and because the role of the Great Royal Wife was of the greatest importance to the succession, the ruling king was usually married to the Great Royal Daughter (who was customarily his sister and the eldest daughter of the previous king and his Great Royal Wife). Inheritance thus passed through the female line; to substantiate his claim to the throne and gain acceptance of his own son as the next heir, each royal heir presumptive had to marry the Great Royal Daughter…Even claimants who had only tenuous links with the main royal line could legitimatize their kingship if they married the royal heiress.
–Handbook to Life in Ancient Egypt, p87 by Rosalie David, Oxford Press