The Hegemony won’t have a “crisis of conscience” over killing any rebel, violent or non. But nonviolent resistance doesn’t rely on the oppressor’s conscience or restraint (notwithstanding self-serving narratives by some Brits and Americans about why the campaigns of Gandhi and MLK succeeded). It has transformed plenty of brutal dictatorships.
Fundamentally, a nonviolent resistance campaign tends to build a broader base of support because dissatisfied citizens can take part at significantly lower risk to themselves personally – not zero risk by any means (there will be plenty of casualties), but way lower than taking up arms. The goal is to provoke non-cooperation and spread it over time to more people, more sectors of the economy/government, and increasingly disruptive forms of non-cooperation. Done strategically, it can be devastating.
Erika Chenoweth has written well on this – see here for a short sample: