There was already a lot of confusion about why The Others didn't take Jack, Kate and Sawyer in 'The Hunting Party' when they had the chance, and now there's even more.

In 'Not In Portland' Jack asked Tom/Zeke why, since they can get off the island, they didn't just take Ben to a mainland hospital for treatment. Tom/Zeke responds with "'Cause ever since the sky turned purple we--" before he's cut off. I'm guessing that means they can't get off the island since the hatch exploded. It's definitely because something changed when the sky turned purple.

They took Jack, Kate and Sawyer BEFORE the hatch exploded. They've known about Ben's condition since before Flight 815 crashed! It makes no sense!

This is really bothering me.

Hmmm, that is a tough one...

well, it could be that the Others intentions for K-J-S were different initially - I seem to recall that when they first arrived on tiny island there was a point made about how they were working on something big - seemingly indicating they needed manual labor help plus they perceived K-J-S to be the main ring leaders of the losties - perhaps those motives combined is why they took the 3 of them at first - but then Locke had to go imploding the hatch, terminating outside communications and so change-o-plan...

but one hole I see there is that Ben told Jack something like "I found out I had a tumor on my spine and then a spinal surgeon fell out of the sky" which kind of leads us to think the Others always planned to take Jack...so yeah, why...

So could it be that Ben thought he was important enough that the dharmies would allow him to leave or send him some help and at a certain point it became clear they wouldn't, they came after Jack?

I dunno - thinking out loud...any other thoughts out there?

Maybe because Locke was with them and for some reason they didn't want him. Aside from Hurley being there to be sent back, Locke is the only difference between the two groups.