The spell was designed to summon Lucifer only as they said in the episode.

Aye, like YED said. It is not the same cage. Only Lucifer were moved there so Michael/Adam are/is still in the real cage.

What bugs me is why don't the boys think of Michael?

Like, "he said he was the elder brother, maybe we should call him up to check Lucifer's story out."

Ugh, I'm beginning to think all the blows to the head have given the boys memory loss problems.

Actually now that I think of it, where was Mike/Adam when the camera DOES show us THE cage itself near the episode start? (the scene where Lucifer looks directly at the camera)

I really wish the show would try taking advantage of Mike more than relying upon Lucifer every, darn time.

I just got finished watching swan song again.
With what we now know, I have to agree that Adam is NOT in the cage.

Jimmy went to heaven after Lucifer destroyed Jimmys body and then it switched from Castiels Vessel to Castiels body.

Adam went to heaven right after the famous line, "Hey! Assbutt!" then torched Adams body with flaming holy oil. destroying Adams body.
At that point, with the same logic, it was no longer Michaels vessel, It became Michaels body.

Everyone can relax now. Adam just isn't in the cage. He's in his own heaven.

Sakii wrote:

I just got finished watching swan song again.
With what we now know, I have to agree that Adam is NOT in the cage.

Jimmy went to heaven after Lucifer destroyed Jimmys body and then it switched from Castiels Vessel to Castiels body.

Adam went to heaven right after the famous line, "Hey! Assbutt!" then torched Adams body with flaming holy oil. destroying Adams body.
At that point, with the same logic, it was no longer Michaels vessel, It became Michaels body.

Everyone can relax now. Adam just isn't in the cage. He's in his own heaven.

The writers haven't confirmed it. Besides, this argument has been thrown around so many times..