ColonelHardisson said:
I think you need to re-read the entire sequence with Celeborn. He came off as, at worst, shaken.
Actually, let's take a look at the quote...
"Alas!" said Celeborn. "We long have feared that under Caradhras a terror slept. But had I known that the Dwarves had stirred up this evil in Moria again, I would have forbidden you to pass the northern borders, you and all that went with you. And if it were possible, one would say that at the last Gandalf fell from wisdominto folly, going needlessly into the net of Moria."
Let's face it, Celeborn has a point - going into Moria was a stupid manuver. Gandalf and Aragorn both knew it, but saw no other choice. Celeborn, hearing what's happened, has every right to think, "My god, these guys are
idiots! If the world hangs in the balance of these people's actions, we are doomed." He says so explicitly - that it seems Gandalf has slipped into folly.
If the saviors of the world are that dumb, you too would think twice about letting them into your lands. At that point, there's somethign to be said for curling up under a rock and enjoying your last moments, or trying to flee to the West.
Note, however, the complete
lack of actual anger. No flashing eyes, nothing. He's quietly speaking his mind. And, a moment later he says it himself - "I spoke in the trouble of my heart."
Do not count the words spoken in one situation as a true report of what he'd have done in another situation. People often say, "If I had but known..." But, really, even one of the Wise doesn't truly know what he'd have done in an alternate reality.
Think about the two basic possibilities of how Celeborn might have known - in one a messenger (perhaps Legolas) goes ahead of the Fellowship, and gives the news. In this case, there is time for Celeborn to
think, and not let his emotions take him where he shouldn't go. In this case, he doesn't almost kill Gimli - he comes to the same conclusion he does in the book.
In the other basic scenario, the Balrog comes screaming out of the Dimrill Dale, hot on the Fellowship's heels. At that point, Celeborn would have every right to keep them out - that is, if he was at leisure to decide, as he'd probably be off fighting the damned thing.