Why did they show Jin in a flashback? Just to confuse us? It seems to me that Mr. Paik must be involved in all this island drama, in addition to Charles Widmore. Perhaps Jin's flashback helps set up a future story linked to Paik.

On the surface, I think it was to remind us who he was and set us up for the scenen in the tent when he forgave Sun saying you did what you did to "that" man. Which isn't to say there is more. Seems on LOST, there is always more.

I think both.

Paik is a player and It was a convenient FB to give us hope that Jin was one of the O6.