I never said that Ryner will become a permanent ally of Tiir. I just wanted to say that the action of saving Tiir at that point would lead to many more deaths, something Ryner obviously is not going to like.

However, you have a point about Ryner not knowing how many people Tiir has killed (and for what reasons) or will kill in the future. I guess it really isn't his responsibility if Tiir goes on a killing spree again, but knowing Ryner, he will probably feel guilty all the same when he finds out what kind of being he saved.