What did Ruth do to deserve to die?
Ok, he slapped Daisy around a bit. But that could easily have been avoided. Because, let's look at it in technical terms.
She had that bounty on her. And, as Major said, anybody except Ruth would have shot her in the back and brought her in dead. While Ruth, no matter his motives, provided her with an opportunity to stand trial.
So would it really have been too much to ask from her to just keep her mouth shut, as a favor in return? Because if she had done so none of those beatings would have happened. Just shut up, that's all he repeatedly asked her to do.
But no, she just had to keep needling him. And that's why Ruth supposedly deserved to die? He didn't kill anybody himself, did he? Quite the contrary.
But strangely enough nobody talks about him. It's Daisy here Daisy there, but that poor fellow being poisoned in a way that made him puke blood all over place and then being shot through the chest to top it off, no one seems to care.
Even though he could have easily shot her himself when realizing what had happened to him. But instead, simpleton that he was, he just gave her another beating instead of putting a bullet in her head.
Strange. Strange world indeed.