I don't agree, I think Tolkien was also talking about individual choices. Remember this bit?

> “What a pity Bilbo did not stab the vile creature, when he had a chance!

> Pity? It was Pity that stayed his hand. Pity, and Mercy: not to strike without need.

> I do not feel any pity for Gollum. He deserves death.

> Deserves death! I daresay he does. Many that live deserve death. And some die that deserve life. Can you give that to them? Then be not too eager to deal out death in the name of justice, fearing for your own safety. Even the wise cannot see all ends.”

And it was that small individual mercy that ultimately saved the world.

and I think that Galadriel could make some choices that she later regrets and has to learn the lesson the hard way about doing evil. This is why I don't see that quote as being against any of Tolkien's principles.