I am no longer going to dredge up the past as if they are confirmation of the present, seeing as how each situation in principle is unique in context, and also the fact that you can choose to do something else, this is supposed to be a game and not only that but what if a bunch of other voters come in and they feel like their agency is deprived if they can't reconsider a course of action simply because you were part of a few votes months or weeks ago where similar action happened?
It is the responsibility of the writer to justify the course of action voted upon in narrative and in prose, and of the voter to attempt to vote for something that they feel would be a course of action that makes sense.
Liberating Slaver's Bay and then pawning it off on the Archon's a year and a half ago without any plans or intentions of helping them keep it from blowing up would have been an incorrect course of action, seeing as even back then Viserys had already realized the implications of outlawing slavery in a slavery driven economy, which is why our conquest took so long in the first place. We had already infiltrated a ruler's palace by subterfuge, grabbing the reigns of power isn't an issue here, it is actually coupling the reigns of power with the mechanisms of rule that is a problem, and to do that you have to have the support (or at least compliance) of the people you rule over. That takes more things than magic or a strong sword arm.
Thus doing the above is not in character.
But Viserys was bitter about Tywin and Robert prospering upon the corpses of his dead family, including children, and has long struggled with the association of callous cruelty his father committed, whatever the justification, with the responsibilities of rule. How do you define what is justifiable violence, punishment, or even out and out, without legal course, murder? How do you manage to divorce madness and instinct from those actions when you do have to take them?
If we keep bringing up old issues near constantly to justify pushing boundaries for nebulous purposes, I dare say the times we have done "nice things" for people would be used as justification to do thoughtless "feel good" actions that actually have nebulous benefit to the people you are being nice to, and may in fact harm them in the long term.
This ship sinks with everyone on it, for Christ's sake.