Sure but it is still a cross-section of what it is — something with a mass of that bowling ball being gravitationally attracted to something the mass of Earth. The blanket is a demonstration of what spacetime is doing (how it’s being warped) by the gravitational attraction. It so happens that you can also sort of demonstrate how another object can be influenced by the bowling ball’s gravity as it’s being gravitationally attracted by something else (like how a small object would be attracted to the moon which is still being attracted to Earth). Given that nothing can really ever be gravitationally unbound, I think it’s a fine demonstration. I wonder if you’re expecting it would demonstrate something it isn’t demonstrating (like how an object in isolation would influence some other object in isolation).
Sure but it is still a cross-section of what it is — something with a mass of that bowling ball being gravitationally attracted to something the mass of Earth. The blanket is a demonstration of what spacetime is doing (how it’s being warped) by the gravitational attraction. It so happens that you can also sort of demonstrate how another object can be influenced by the bowling ball’s gravity as it’s being gravitationally attracted by something else (like how a small object would be attracted to the moon which is still being attracted to Earth). Given that nothing can really ever be gravitationally unbound, I think it’s a fine demonstration. I wonder if you’re expecting it would demonstrate something it isn’t demonstrating (like how an object in isolation would influence some other object in isolation).