I kind of understand it because it has the protein and the sugars. But his "dumbed down" explanation is just plain dumb:
"It's pretty simple," Barwis said. "What did you drink when you were a baby? When did you grow faster than that? Never did. Evidently, Mom and Dad knew right in the first place."
Maybe he's forgetting that there are other chemical reasons that you grow so fast when you are a baby. Not just because you were fed milk lol.