Your console can output whatever you want, but the devs still decide what resolution their games run in.
Then why is the statement that running Scorpio at 1080p opposed to 4K wouldn't net any benefit so inaccurate?
What's being discussed is:
1- Devs can target 1080p and the console will just upscale the image.
2- Devs will create profiles for 1080p and 4k, where, when running at 1080p the game has enhanced graphics and/or framerate.
3- Devs must always target 4k and when the console is running at 1080p it'll be the same game without any enhancement.
If you take Spencer statement from the other thread you can rule out number 2, because he says that only with a 4K TV the console makes sense.