It may look that way, but no... the crush sleeve is only there to apply pre-load. In fact, when measuring pinion depth, it is done without the crush sleeve installed.
Since the rear bearing's race is in a fixed position, and the bearing is in a fixed position on the pinion (pressed up against the shims, which are up against the back side of the gear), how can the depth of the pinion gear be altered by compressing the crush sleeve? Where's the movement occurring that would change the depth?
And, in fact, pinion depth measurement is done without preload.
Yes - it's the amount of pressure being exerted onto the bearing. With 50 pounds or 500 pounds of pressure on a bearing/race, the distance from the outer edge of the bearing to the outer edge of the race is going to be the same.