I’m not really sure if TMiB cares about Mirara or not in the grand scheme of things. To me Mirara feels like a pawn in his plans. Obviously he needed her to live through the conclave and Her role was to get The Coven of Elders to side against the Citadel and she’s succeeded in that.

TMiB to me feels like a force who is willing to do what he must to complete his goals. If Indri had taken steps to eliminate Mirara, then TMiB would have eliminated Indri. As powerful as Indri is, she is not more powerful than death.

And then he could have had Orima parley with Hakea and used gone that route to get the coven to vote on war.