I’ll give it a shot. Ethical right or wrong can be measured against absolute or relative standards.
Christian fundamentalists in my experience have stated that right and wrong are deity derived, never change and are absolute. The bible is “as is” no reinterpretation allowed. The 10 commandments are absolute. Murder is always wrong regardless of circumstance.
Relativism argues, that this is simplistic and doesn’t answer our sense that the situation may change the right answer. We accept that killing in self defense is OK. War has been promoted, and even biblically commanded (Joshua).
One weakness in relativism is that it becomes easier to rationalize certain ethical positions, and that allowing the unwashed masses to “wing it” opens the door to potential nasty things.
Ethical stances are like religions, and the examples you cite, are similar to extremists. I believe we are poor judges of right and wrong, and that some situations require much maturity and forethought. We are easily corrupted, and you need look no further than the headlines for proof. Our principles are easily tossed out with our integrity for the next treat.