I don't see how Rag is refusing to play the story. He wants to ask a party member to leave. He doesn't want to initiate murder to make it happen.
I don't know how many times it has to be repeated Shadowheart's absolute duty is to protect that artifact with her life and deliver it to Baldur's Gate...it literally does NOT matter what you want, that is the choice presented by the DM. That is a hard rule set by the DM, either she tags along or you HAVE to kill her for it. That is not a suggestion, that is not a maybe, that is a condition set in stone by the background, character, and mission of the NPC holding the artifact. Now, either you accept the rules set by the DM or walk from the table. Very simple.
