This report refers to mouse sensitivity in terms of change in weapon facing/direction/vector/angle from a given mouse movement. It does not measure mouse movement in terms of screen space/pixel change.
In Arma 3, mouse sensitivity is inversely linked to the magnification of the current view. While this quite normal for computer games/programs with variable zoom, the resulting effect is that using a high magnification optic (high zoom scope/sight) allows the player to make minute aim adjustments that aren't possible when using low magnification optics.
While weapon sway or recoil remain constant for all optics, correcting for these effects, aiming at a given target and tracking moving targets is easier with high magnification optics.
This means a high magnification sight is almost always better and easier to use than a low magnification sight.
In reality, the magnification power of sights have no effect on the users ability to control a weapon.
Mouse control of the players weapon should not scale with weapon optic magnification.
High magnification sights should be difficult to use when the weapon is not stabilized.