(with caveat for the liklihood that Shadowheart is brainwashed and is an otherwise heroic Selune worshipper, who is also probably Selune's chosen, and Shar's chosen, and the living avatar embodiment of the proof of the darkmoon heresy, destined to bring balance and unity to the twin goddesses. Tell me I'm wrong, I dare you)
Et tu, @Niara?
I'll say it. You are wrong. Larian can certainly present things this way with SH, but as a 'good' character, perhaps even as a Selunite character, my PC would reject such a lame-ass storyline and consider her to be a murderer who betrayed Selune. And I would expect that Larian will provide me, the player, the opportunity to play my 'good' character in this way and not block me from reacting this way to such a lame-ass storyline for SH.