People can have alters that are rocks. Alters can be whatever was needed at the time. A person I know has an alter that believes she is a tree. When she was being beaten that part of self believed a tree trunk couldn't be hurt.

We have an alter who is believes she is a dog. Because she was made to eat out of a dog bowl and other more triggering things.

Is she really a dog? Of course not. But she took on the role that she was forced to take on. I can certainly imagine a scenario where an abused child took on the belief that it was better to be an inanimate rock than a tortured young child who had no hope of escape from abuse for years and years stretching into the future.
I would choose to be the rock, any day.

I am a little annoyed because it feels to me like you are denying my own abuse. I am reminding myself that your personal experiences and beliefs have no relation at all to my lived reality.