Charlie died because Desmond told him to? by Sawyer's S****-eating Grin

I just rewatched "Greatest Hits' and "Through The Looking Glass" and have a BIG problem with Charlie's fate. I'm not desperate to have him back or anything like that; dead is okay if it's a necessary part of the storyline. It's just that while watching the events of his demise play out again it seems obvious that he didn't even try to save himself. Why not?

Because Desmond told him he had to die in order to save Claire??? If so, then he's got to be the most valiant Lostie so far, because it seems to me that he could've easily survived had he only tried a little harder.

First, he closed the door to keep Desmond out of the room. Des had been grabbing the SCUBA gear for their escape when he heard Penny's voice and came running. I'm a diver and believe me, I could get my gear ready pretty quickly if my life depends on it. All you really need is the air tank connected to a regulator to make an emergency escape. Besides, all Charlie had to do was leave the room instead of locking himself in. (provided it could be secured from the outside) Then he could grab the air tanks and leave with Desmond. Considering how long it took the room to fill with water, it would've taken WAY longer for the entire station to fill up and they could've both gotten out. Heck, even without the tanks they could've just swam out... it's a whole lot easier to swim up and out than down into the station and they BOTH managed to do that without tanks.

Secondly, when the grenade exploded it wasn't an instantaneous flooding of the room he was in. There wasn't even enough force from the explosion to knock him out. Another poster here also noted that the room would NOT have filled with water once the level was higher than the porthole. There would be an air pocket at the top of the room and Charlie could've escaped through the large porthole once the water had stopped entering the room.

So not much of a theory, except that I have to call BS on the inevitability of Charlie's death in this series of events. All of Desmonds other visions had Charlie dying in much more believable scenarios. Charlie was so resigned to his fate that he gave up too easily, IMO.