GRAY-HAIRED MAN: Do you have any idea how badly I wanna kill you?
BLOND MAN: Yes.
GRAY-HAIRED MAN: One of these days, sooner or later... I'm going to find a loophole, my friend.
BLOND MAN: Well, when you do, I'll be right here.
GRAY-HAIRED MAN: Always nice talking to you, Jacob.
JACOB: Nice talking to you, too.
JACOB: You like it? I did it myself. It takes a very long time when you're making the thread, but, uh... I suppose that's the point, isn't it?
LOCKE: Hello, Jacob.
JACOB: Well, you found your loophole.
LOCKE: Indeed I did. And you have no idea what I've gone through to be here.
BEN: Have you met before?
LOCKE: In a manner of speaking. [Whispers] Do what I asked you to, Ben.
So, if it's just a theory that Locke = MIB (and I've heard that across the wiki), how can the above be justified?
Which one is more likely (IE, simpler): MIB is now Locke, or a resurrected Locke just happens to suddenly act just like MIB-to the point where he also wants Jacob dead-and is recognized as also searching for a loophole by Jacob?