Question

“Even though the Oral Torah was not written down, Moses our Teacher taught it in its entirety in his religious court, to the seventy elders. And Eleazar, Pinchas, and Joshua—all three received it from Moses. And to Joshua, who was the disciple of Moses our Teacher, he transmitted the Oral Torah and instructed him concerning it. So too, Joshua taught orally all the days of his life. And many elders received it from Joshua. Eli received it from the elders and from Pinchas. Samuel received it from Eli and his religious court, and David received it from Samuel and his religious court. And Ahijah the Shilonite was one of those who left Egypt, and he was a Levite, and he heard from Moses, and he was young in the days of Moses, and he received from David and his religious court.” [Raavad’s gloss: “Abraham says: This is not correct; rather, Ahijah the Shilonite was a member of David’s religious court.” ]
Maimonides took the aggadah about Ahijah’s long life literally, and created something puzzling and strange.
Ahijah was young in the days of Moses—fine. But what happened from Moses until David? He didn’t grow up? He only grew old and his days drew near, and then suddenly remembered to receive from David and the religious court???