I saw him shoot in person, once, he was using aluminum. I believe it was a matter of what he thought was best at the time. He used aluminum on his elephant arrows, but Ben Pearson made around 1000 wood arrows to go to Afica. Hugh Rich hand checked them all.
He would tear up a lot of wood arrows in practice, so the Easton Aluminum worked best in demonstrations. I think he would use them for show, but not necessarily hunting (rattled too much in the quiver). Unless he was tearing them up, then he would stop using them.