Marluxia is killed (in the GBA he actually explodes into petals, probably the inspiration for the “consumed by the element” idea in KH2), and Sora returns to the hall, where his first response is to… seal the door with the Keyblade? If there’s something worth sealing away back there, they sure didn’t spell it out to me. Am I wrong? Is he afraid of the room itself and its starry expanse? Or is he just that angry? You can tell from this screenshot and the events of the last entry that Sora is furious, I don’t doubt that, but I still don’t see what this accomplishes. Donald and Goofy even pre-empt his actions by closing the door in the first place, and they aren’t angry at all! You have to make up an answer to make this work, because the game isn’t talking. Sora’s response isn’t that extreme on its own, but it is an extreme response to the stimulus, which is to say: no stimulus at all!
(ShardofTruth made an interesting point about this scene in the Retrospective’s thread at KHI. I’ll discuss it again towards the end of the KH2 Retrospective, but if you’re familiar with the series already, you may want to check it out here.)
Let’s not even begin to talk about why Sora doesn’t just imprison villains in rooms to begin with. From what we see in the series, while the Keyblade can unlock anything, it’s only ever used to lock specific locks. I’m just not sure why this is one of them!