Board Thread:Fanon Canon 2/@comment-25152698-20140923215106/@comment-25152698-20140923235411

Key thign here is "After reaching Kiri's outskirts."

And also, Kimimaro is never said to be affiliated with Kirigakure, not even in his infobox, because the Kaguya clan did not belong to Kirigakure. They simply tried to destroy it, to show their power.