And that's understandable. I'm pretty sure we've all done things across the course of these quests that we disagreed with as people. (Hell, we had a big fight about one such thing not 500 posts into the game, as I recall.) However, the thing to keep in mind is that this is Iku Quest. We are playing a character that is going to know certain things and act certain ways, and not know certain other things and not act certain other ways. This quest was designed with Iku's strengths and weaknesses in mind, as was Maribel Quest before it, as was Utsuho Quest before that. It is meant to be played knowing the things Iku knows and behaving the way Iku is supposed to behave. It might as well be Omniscient Lightning-Throwing OC Quest if we starting using outside knowledge and controlling based on our behavioral preferences instead of Iku's.
There have been plenty of "easy" solutions so far. We could have beaten Tenshi into submission to make her behave, we could have left the poltergeist to rot on her own, we could have beaten Remilia into submission to take the islands back, and so on and so forth. The idea behind it being Iku Quest is that playing Iku means none of those things were intended to happen. It is for this same reason that we're not supposed to use spreading lies as a way of sustaining the poltergeist's existence.