This is not due to any inability to see it as evil. They are oppressed by it, psychologically. They are running away. They ascribe powers of moral contagion to evil, and think they are consciously resisting that contagion. Judgment involves assuming a role of power and responsibility that they fear will corrupt them.
Is this an ethical error? Yes. An epidemic one. But then, error is the ordinary state of mankind. They can't be reached by telling them their moral sense in the matter is intellectually flawed. They can't be reached by calling them to responsibility, when they consciously shrink from it. What they need is a way to combine moral judgment of men and things with underlying respect or love of them.
This is not an obvious point, either philosophically or ethically. It is something they simply have not been taught by the reigning philosophy they are constantly exposed to. At bottom it is a misdiagnosis of totalitarianism, and because of it a misformulation of the principle of tolerance. They think they must leave open the possibility the other side is right, or deny that right exists, to avoid annihilationist political consequences.