He once said, and I'm paraphrasing here, "We've forgotten the Bible, and the Protestants haven't. The Protestants love God as much as we do. Maybe God is keeping the Protestants around to hold our feet to the fire and keep us honest."
His comment about canonizing Billy Graham was made in that same context. Sheen saw Graham as a Protestant prophet, and he saw that in the larger context of God having a sense of humor.
God always has a plan.
P.S. I came to a similar conclusion as Sheen before reading your paraphrasing of him. It's a relief to be in such good company. Thanks for posting that!