I know the post is a joke, but the main difference is that Luke was on the winning side at the end of ep 6, redeeming his father and avenging old Ben, while OB1 saw his entire world, the Republic and the Jedi, being destroyed at the end of ep 3. He became a target and "traitor", so hiding was the only sane choice.
Also, while OB1 readied himself to fight Anakin, it was the latter that jumped to strike first. Luke tried to kill Ben while the kid was asleep.
As others said, Luke retiring or wanting to be left alone because he fucked up big time isn't a problem per se. The way his reasoning is treated, especially for trying to kill Ben Solo, is what left a LOT to be desired. "Oh, I had recurring nightmares that he'd fall to the dark side". Well, did you confide that with anyone? It's not like Yoda, Anakin or Obi-Wan's force ghosts would rat him out. - My memory is hazy, but I don't remember him saying, or the movie showing, what he tried besides cold blooded murder to avoid such a fate.