There was a quote by Harlan Ellison that I read yesterday to the effect that story writers these days have learned their craft too much from watching television and lack a genuine grasp of structure and pacing, with the result that the dramatic (or melodramatic) often rules over realistic behavior and common sense- things are shoehorned to fit the way the author wants them to play out rather than the author following them through to their logical conclusion. Ellison was specifically referring to comicbooks, and put it much more succinctly than I just did, but I think that's very much applicable to shows like Lost in general, and this episode in particular (even more apt when you consider that at least a couple of Lost's writers are comic writers themselves).