No. He had to fight Vader and kick Vader hard or Vader's line in Star Wars, "I've been waiting for you, Obi-Wan. We meet again, at last. The circle is now complete. When I left you I was but the learner. Now, I am the master." would not have made sense. What they should have done, though, is bring in the Inquisitors or some other overwhelming force that would have made Obi-Wan run and have to leave Vader alive.
It's an old school morality play. The evil guys have to be really evil and the good guys have to be squeaky-clean. White Hats only, non Grey. If Vader was killed with one stroke, that's one thing. Killing him when he's helpless is quite another.
How is letting him walk away to keep killing a good act?
It still doesn't really make as much sense as them just not meeting at all between RotS and ANH.
Because, like I said, it's an old school morality play. Doing an evil act, for a good outcome, isn't considered good.
So something we have to remember....a Jedi's morality is not the same as standard human morality. Remember that these people wield powers normal humans can only dream of, and they literally have this "voice" in their head that seems to whisper its will to them. They get visions of crazy possible futures, etc etc. Aka there is nothing "normal" about being a force user.
That's assuming killing evil is an evil act . Is it? Or, trying to imprison him (admitting I have no idea how that works in star wars, but in theory is an option).
It's like being required to be tolerant of hate, in the name of tolerance. I'm not required to do that.
