Are all points on the surface of a non-rotating neutron star the same distance from the center (to a good approximation) only if something is observing it? Is there ever a time when it just decides to ignore the laws of physics and become angular?
Do objects follow the laws that our descendents wrote in a paper, otherwise they go to jail or smth? There is a lot of lack of rigor in our language, stemming from the fact that science "began" with a christian perspective that the universe obeyed the "laws of god", and it would be pretty cool for us to find such "laws", as if a celestial court existed that punished these and those particles if they dared disobey.
But I'm diggressing, flame me at will. Back to your point, no I'm not saying that things stop existing the moment you close your eyes. I'm saying that they don't care what you call them or what you decide they should do while calling it a "law". Is earth spherical, or not? Are the atoms of the surface (And what exactly constitutes the surface?) of the neutron star (and where is this "non-rotating" neutron star exactly located, apart from inside your own abstractions?) exactly placed in a spherical position?
No, you yourself agree they are not. They could as well be defined fractally, it depends upon what we want to study, to inform, etc.
I have an object that is approximately cubic in front of me too. See? Here it is!
[awkwardly intimate image of a cube trying to make a point]
Is it only in my head that this thing has approximately planar surfaces, each of the eight vertices a union of three orthogonal planes, each of the edges approximately the same length?
Read what I wrote. Abstract concepts that were invented by humans are very useful to categorize stuff that we see out there. I agree that if you choose to categorize your object as a "cube" then you are speaking english correctly and you are conveying useful information to me.

Topology is an empirical concept with deep roots in mathematics, and therefore I find it very difficult to agree with your claim that "shape" exists only in our heads, since you seem to have the same definition of shape as I do. That's like saying that math and physics suddenly breaks down if nobody's looking.
edit: I understand you're saying that there are no platonic solids in nature, simply because you can always find a deviation from perfection if you zoom in enough. And this I agree with. The event horizon of a solitary non-rotating black hole would probably be the closest thing to a perfect sphere in nature. But my point is that just as a perfect sphere is a mathematical entity, any random object has a topology that is also capable of being defined in the same way. One of the beauties of the principle of superposition is that any object can be represented by a sum of multiple equations. And that makes shape a concept that is not just an artifact of human perception.
Topology is an abstract concept that has certain needs that you can't guarantee on your objects. I'm not saying that math and physics aren't useful. I'm saying they are constructs, they
are not reality. They are
models. Models do not "exist out there" as "objects".
This is an ancient mistake, like saying that things "exist in themselves".
I have a question for you. Does an orbit of a planet "really exists" outside the human mind?