Luke found out in ESB that the most evil darkest soul in the galaxy was his father, who also was responsible for killing his aunt and uncle in cold blood, and he himself if he was there too. All this after idolizing the man as one of the greatest pilots in the galaxy, a great man and friend to Old Ben Kenobi. Why didn't he just have a break down then and there. He just lost his hand to boot.... He didn't run and hide then cause he was always meant to be the hero. No matter the odds or the atrocious acts he would witness towards himself and his friends, he fought on. He stayed to save his buddy Han, and try to redeem his father. Not seek revenge and kill him, but redeem him and turn him back to the light.... After knowing all he had already done.
Sorry, having bad feelings and visions about little sweet Kylo, who hasn't actually done anything evil yet, knowing Snoke was the one manipulating him, serves as the worst justification that a wiser older more experienced Luke would try to kill Kylo in his sleep rather than help him. And then, when he's caught in his moment of weakness by Kylo, he then cowers in shame to let his responsibility wreack havoc on the universe and ultimately kill Han... Rather than writing the wrong like he always did before.
Yep sounds about right... GOOD deep characterization and storytelling...
