The primary determinant of scapular position is shoulder position, not upper back position.
Proper scapular position should be dictated by what your shoulders are doing, not what your upper back is doing. If your shoulders are overhead--or beyond overhead (hollowback handstand, bridge, etc)--biomechanics dictate that the shoulder blades should be elevated (shoulders shrugged up) and in at least 60 degrees of upward rotation. If you're in a contortion handstand (shoulders at or near 90 degrees, i.e., "piked") or in a cheststand with arms at your sides, the scapula should be in a slightly retracted position. This serves to protect the rotator cuff.