I agree that he was the one who took the fall, but he was absolutely guilty, the only problem is they didn't go after more of those involved and Calley's light time served.
Whether or not you believe he was following higher orders, or whether or not you believe he ordered his subordinates to murder, he admitted to murdering civilians. Members of his unit committed further murders and rapes of innocent men, women, and children.
We condemn ISIS murders and terrorist attacks, we look on the back and fourth cleansing of villages by Nazis and Soviets on the Eastern front as horrific, and we need to hold Americans to a higher standard, or at least the same standard. Millions upon millions of Americans served honorably in Vietnam, there is absolutely zero reason we should be OK with those that committed that atrocity.