Obi-Wan: Of course, you're Luke's only living relative. Where else is he supposed to go?
Uncle Owen: I was thinking anywhere else. This is absolutely the first place that anyone would look for him.
Obi-Wan: Who's gonna be looking for him?
Uncle Owen: Hmmm maybe ANAKIN?! My psycho half-brother who is now Emporer Palpatine's apprentice. Remember him?
Obi-Wan: Uncle Owen, I chopped off his legs and watched him get all burned up. It's not like anyone has the technology to heal him.
Uncle Owen: What?! They absolutely do. We can travel at light speed through outer space, we sure as hell can heal some burn victim who has magic powers. I've got a bad feeling about this
Obi-Wan: I wouldn't worry. It's not like he'd be able to find you.
Uncle Owen: Oh yeah, I'm sure the Emporer's right hand man would never think to check his home planet, his only living relative, or the only other person in the galaxy named "Skywalker." Can't we call him something else? How about Luke Smith?
Obi-Wan: Luke Skywalker. Check the birth certificate.
Uncle Owen: But if we named him ANYTHING else, it might be at least slightly harder to find him.
Obi-Wan: What are you even worried about? Anakin would never hurt anyone who didn't deserve it.
Uncle Owen: Didn't you say he killed a bunch of kids?
Obi-Wan: Ohhhhh right. That. Yeah, he killed a ton of Jedi toddlers we call them Padawans and yes,
they are the cutest things in the galaxy. They've got these mini-lightsabers and little robes. So adorable. But yeah, he slaughtered them all without even a hint of remorse.
Uncle Owen: Why couldn't he live with his sister Leia? She doesn't have to keep his last name, or live on a desert planet ruled by giant slugs where all we have to drink is blue milk.
Obi-Wan: No, trust me, this is the best way. Don't worry I'll be close by if you need anything. I'll have you know I learned a pretty amazing power in case ol' Anakin ever comes back.
Uncle Owen: Yeah, what is it?
Obi-Wan: Right when he thinks he's got me I'll let him slice me with his lightsaber and kill me. But then I'll be a ghost!
Uncle Owen: HOW WILL THAT HELP ANYTHING?
ya know. I can give Luke advice and stuff. Like "use the force." But all ghost-y.
Uncle Owen: Couldn't you tell him that while you're alive?
Obi-Wan: No, dying is a solid plan. If it makes you feel better, I know where the most powerful Jedi in the galaxy is.
Uncle Owen: Where?
Obi-Wan: Wandering around a swamp, lifting stuff with his mind. Also, he's a muppet. A dyslexic muppet.