Restriction on child pointer of a restricted pointer?

The article mentions:

Restricted pointers can be copied from one to another to create a hierarchy of pointers.
However there is one limitation defined in the C99 standard.
The child pointer must not be in the same block-level scope as the parent pointer.
The result of copying restricted pointers in the same block-level scope is undefined.

And then it provides an example:

{
  vector3* restrict position   = &obj_a->position;
  float*   restrict position_x = &position->x; <-- UNDEFINED
  {
    float* restrict position_y = &position->y; <-- VALID
  }
}

Tho, later on, it has another example:

void
move( vector3* restrict velocity, 
      vector3* restrict position, 
      vector3* restrict acceleration, 
      float             time_step,  
      size_t            count, 
      size_t            stride )
{
  float* restrict acceleration_x = &acceleration->x;
  float* restrict velocity_x     = &velocity->x;
  float* restrict position_x     = &position->x;

I thought now the restricted parent pointer position is in the same scope as its child pointer position_x, no?