I don't think it's a bad idea, as long as it happens when Sai finally starts to fall in love with Grayson. We can make it so that the faux Orion is exactly like the real Orion in every way, and it offers a good explanation on what supposedly 'actually happened' the day Orion died.
If he travels with the group, tension will mount. (Mainly because Sai is with Grayson now. We can make it so that he still flirts with Sai, etc.) I really like the idea of screwing with everyone else's emotions too X^X