Why on earth would anyone use anything other than a front surface mirror in a serious optical system? But you'd still have to polarize the light in the first place. So no answer there. ... A long time ago there was an analog predecessor to holographic images, a Dupont Vectograph film,which you could enlarge onto, with polarized light I think, and create a 3D color print. A very complex process; and of course, nothing directly related to the present question, but interesting anyway. ... So I'm just going to take a wild guess and suggest that this guy might be practicing some kind of old wives' fable about printing, with no scientifically real advantage.