Here's a viewpoint on whether to mind our own business "when we believe there is a terrible injustice" from a world-class authority. You may have heard of him. (This quote was included a couple of days ago in the free email from A.Word.A.Day.)

"If you are neutral in situations of injustice, you have chosen the side of the oppressor. If an elephant has its foot on the tail of a mouse and you say that you are neutral, the mouse will not appreciate your neutrality."
-Desmond Tutu, clergyman (b. 1931)

Personally, I don't see how ignoring a grave injustice would help the efforts of people trying to correct it. The descriptions of her comment sound measured and honest.