User blog comment:ND999/Lore Hypothesis, Mt. Targon, Guardian Sea and Shadow Isles/@comment-3087008-20141115152137/@comment-24613667-20141117201745

If Kallista was the Avatar of the Moon and was present when the Shadow Isles went crazy, she could have been blamed for the event which then led to the extermination of the Lunari. Maybe tensions were already high between the Solari and Lunari, for whatever reason, and the Solari took the opportunity to condemn the Lunari.

No idea how that'd fit into everything else, but I suppose it might be a possibility.