"for others" in my original statement is a euphemism for one's fellow citizens. So no, the mercenary is not doing the same thing.
And truthfully, neither is the soldier. The military hasn't been acting for benefit the general public in a long time, if ever.
Here is a second bit of wisdom that the WW2 paratrooper taught me as a child: "Don't confuse the people who fight wars with the people who start wars. They are not the same people. Soldiers don't get to choose what wars they will fight, what Presidents they will trust."
Plus the mercenary can break their contract and leave if they do not like the mission or lose faith in their leadership/mangagement
Ignoring for a second that you are saying soldiers are better because they can't turn back when they realize that they are actually committing horrific crimes, ...
One of the few privileges that a U.S. soldier has is to refuse to commit a horrific crime. Save the hyperbole for political rants.
... I'm not sure that a mercenary quitting would be a great idea for their well being, since whoever hired you would have access to other mercenaries.
Other mercenaries who probably also lack confidence in the mission and/or the leadership and after re-calculating the risk/reward see breaking the contract as the best outcome.