Ridiculous question, but would you still think Celestia (in some alternate universe from the show from across the multiverse) is good if she willingly taken the essence of Bhaal to become the new Lord of Murder from Dungeons And Dragons?
She was good and thought she could use the essence of Bhaal for good. But she went insane and murdered everyone and wiped all life in Equestria, leaving no one but herself to be alone forever.