Any ranged projectile/beam/pulse-firing weapon (with a range greater than ~6 meters) can use, and benefit from, improved sights of whatever type your T.L. allows.
After all, even a straight-line, virtually-instantaneous, no gravity-droop/wind-drift weapon like a laser rifle will benefit from the shooter being able to more clearly see his target, and precisely define where the impact point will be. For Laser weapons, not needing to calculate "lead", I would reduce it to a +3, rather than the +4 of book 1.
Actually, instead of a +4 at long/very long and none at medium for both telescopic and electronic* sights, I give the modifiers as:
on rifle/carbine
Telescopic sights: +2 long, +3 very long
Electronic* sights: +3 long, +4 very long
on pistol/SMG^
Telescopic sights: +1 medium, +2 long
Electronic* sights: +2 medium, +3 long
bows/crossbows
Telescopic sights: +1 medium/long
Electronic* sights: +2 medium/long
* allows normal vision at night... within the FOV (field of view) of the sights. Also displays range info in the sight, as it incorporates a laser rangefinder, which may be disabled, but this drops the modifiers by 1. On Laser weapons the rangefinder has no effect on accuracy, so the laser rangefinder is always treated as disabled for modifiers, but it can still be used to gather range information.
^ even though an SMG is more of an area weapon, the sights can still help place the center of the shot group more accurately... but dispersion is too large at very long range for much improvement, so the modifier there is only +1/+2.
As any physical shock/vibration transmitted through the frame of the weapon can be eliminated with the proper isolation mounts for the sight, the only exception would be for a weapon that creates a severe atmospheric shock/vibration. Those high-shock weapons would rapidly render the sights inaccurate or inoperative, unless used in a very thin, trace, or vacuum atmosphere.
Of course, that is my interpretation... as you asked.
Others might rule differently.