So Plato was a quantum physicist.
This is really just the same thing philosophers have been suggesting for millennia.
Perception is reality.
To use their example, that the moon doesn’t exist until you see it, and measure it, well, all the atom, and subatomic particles, and those things we define as mass and energy, between the moon and the space around the moon is no different... until you start to define differences, like density of matter, or start to sense the energy, or start to quantify mass. Otherwise, all existence is just existence, the differences in all the properties are only significant when someone comes along and perceives them, or measures them.
Until someone comes along and decides for themselves where the moon stops and everything besides the moon starts, it’s all just whatever it is; Nothing, everything, anything.
Ah, but Plato realized that there has to be a first observer, the ultimate cause. This is why John the Evangelist defined the Christ as the Logos-God, He by whom the universe was created.
If this parlor trick means that Bob and Alice aren’t merely picking which branch of time-space-probability they are traveling down, but are actually causing the particle spin to become determinable, then Bob and Alice just proved the existence of the Logos-God, He who speaks and therefore the universe exists.