I get what you are saying but what has me confused is the way Spencer worded "It’s nothing like Xbox 360 backwards compatibility right now — there’s a lot of technical wizardry involved in that. We didn’t want to have to do that again."
Isn't 360 BC software based? If you doing a software based compatibility again for XBO on Scorpio why would you word it like that?
The only thing I can figure is he is referring to having to essentially run the entire Xbox 360 OS on Xbox One hardware just to get games to work. Maybe that is what he is referring to by "do that again".
Edit: But still this doesn't answer how easily 360 BC will translate to Scoprio? Or how to emulate esram?
Right, I understand where you are going now. It's important to note that PS4 Pro's solution is not the only solution that is available to perform hardware backwards compatibility; It may just be the one that made the most sense for their needs and targets. MS's hardware compatibility can be developed entirely differently to meet their requirements and needs.
It will be interesting to see how MS tackles BC compared to how Sony is.