The X-pulldown is the ultimate shoulder-friendly exercise. The instructions are clear: start thumb-down (internally rotated at the shoulder), finish thumb-up. (externally rotated at the shoulder).
By moving from a thumb-down position to a thumb-up position, we've added external rotation to the pulldown, so we've made it into a very joint-friendly spiral while adding a little rotator cuff twist.
While performing the movement, push your chest toward the machine. You just retracted the scapulae, but you didn't need the old school cue, "pinch the shoulder blades."
You can't push your chest forward and shrug your shoulders simultaneously. Pushing the chest forward is retraction, while shrugging is elevation. So if you want to eliminate shrugging at the top of the pulldown, cue chest to bar, not bar to chest.