Lost in Tv Guide

This is a blurb about Lost from TV guide:

I recently saw Malcolm David Kelley, "Walt haircut" and all, hawking chicken snacks in a Tyson commercial. It didn't fill me with a lot of hope for his future on Lost. Care to comment? — Adam
MATT: Did it occur to you that MDK was working the Walt 'do because he recently filmed an episode of Lost, scheduled to air Feb. 25? Just don't expect Michael's son to factor into Ben's mission to return select former castaways to the isle. As Michael Emerson tells us, "The writers would say that Walt ... left the island at a time that wasn't key. It's not just about the six who left; it's about when and how they left."

What I find interesting is what Emerson said, 'It's not just about the six who left; it's about when and how they left.' So does this mean Desmond and Frank Lipidus also have to go back? And if so can Des take Penny and Charlie with him? I don't think I could take them splitting up Des and Pen. And why John Locke's 'dead' body? He didn't leave at the same time or in the same manner as the Oceanic Six...or did he? So many questions, but I believe most of this stuff will be resolved very soon. The Oceanic Six should be back on the Island by episode 7, 316. Which I believe is the Arjira Airways flight they take to get back to the Island. What's your thought on who has to go back to the Island and why must they go back?