Well, from a technical standpoint, if a game is developed with the exact specs of the Xbox One in mind, it might have issues running on the Scorpio simply because the Scorpio has different parts. So in development of Scorpio and the OS that will run on Scorpio, they need to make it so that Xbox One software running on Scorpio will behave as it should even though it's different hardware. This is not necessarily emulation.
In application, this might actually be a really simple process if the hardware is similar, but if they are going to tout that all X1 games will run on Scorpio, they need to verify it, and that is the job of the Xbox Compatibility team.