I suppose if they really sideline the relics and make it into a half spiritual journey to develop Ryner, then it would make a whole lot of sense. I'm not sure what Sion intended, but for now I'm quite sure he really wanted to find relics and also probably wanted to keep Ryner sharp enough to be of any use, should the need arise. Maybe he even foresaw Ferris tough and fit enough to stick with Ryner through all the troubles. It would have ended pretty badly for Ryner if his companion had abandoned him.

However, I doubt Sion thought Ryner would lead the country. He might have written a nice book but otherwise his hardly suitable. Too lazy and people would be afraid of him.