Problem with non kinetic rigidbody and interpolation

Not sure if it is a normal behavior :

For the two exact same rigidbody (with interpolation set to interpolate), having it kinetic or not will affect interpolation.
The non kinetic rigidbody will stutter if timescale is reduced, not the kinetic one. (i suppose timescale make it just more obvious)

i was able to reproduce it in version 2018.3.0f2 and 2019.1.0a10

Rigidbody rb;
    void Start()
        rb = GetComponent<Rigidbody>();
        Time.timeScale = 0.2f;
    void FixedUpdate()
        rb.MovePosition(rb.position + transform.forward * 10.0f * Time.fixedDeltaTime);

This makes sense to me. MovePosition() and interpolate (on a rigidbody that is kinetic) will have a smooth transition between the positions.

On a rigidbody that is non-kinematic, MovePosition() is essentially the equivalent to just moving the transform. It will just skip to the exact position, instead of a smooth transition.

MovePosition() is useful for smooth transitions with kinematic gameObjects, but not vice versa.