That last action is the only one that is hard to defend. I personally don't think he was going to do it. Mental breakdown as was stated. That combined with the what he said before - something along the lines of him only killing demons.
Though if we say he was going to go down that road, I'll have to say that almost all the men in this story aren't great moral figures. I've not read the source material for this, but if you read the first chapter of the (broken English) manga, you will get a different view of how Akatsuki does things with the maids he fought. This is probably a straw man argument, but it's the best I can offer atm. The author does have to tell us who we should be supporting right?
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