Waddell presents a strong case for his theory.
"This critical record by Manis-Tusu (Menes) of his crossing the Arabian Sea in ships with his great armies after his reconquest of the Indus Valley and his conquest on the Arabian side of thirty-two confederate kings, and his advance to a country of Silver Mines, the name of which is lost, and to the mountain beyond the sea of the diorite rocks, which we shall find is Magan, in the Sinai Peninsula at the head of the Red Sea, which was afterwards regularly reached by ship from Mesopotamia, is all of immense historical importance with reference to the Red Sea route by which Menes reached Upper Egypt with his metal-armed warriors and Sumerian civilization."
Menes is buried at Abydos. Waddell claims that Sargon was king of the all the lands from the Indus to the Nile and his family is also buried at Abydos. That newly-found sarcophagus obviously was unknown to Waddell. Archaeologists can't place its owner. Sargon was known as Sargon the Great. Would it fit?
Below is Waddell's diagram of ancient trade routes as postulated by yourself. Boats from the Indus through the Bitter Lakes Canal and up the Nile to Abydos.