The original was Eliezer himself, in How to Seem (and Be) Deep. I'm more fond of TheOtherDave's analogy, though, since I think the baseball bat analogy suffers from one weakness: you're drawing a metaphorical parallel in which death (which you disagree is bad) is replaced by something that's definitely bad. Sometimes you can't get any farther than this, since this sets off some people's BS detectors (and to be honest I think the heuristic they're using to call foul on this is a decent one).
Even if you can get them to consider the true payload of the argument (that clearly bad but inevitable things will probably be rationalized, and therefore that we should expect death to have some positive-sounding rationalizations even if it were A Very Bad Thing), you still haven't really got a complete argument. That baseless rationalizations might be expected to crop up justifying inevitabilities does not prove that your conversation partner's justifications are baseless, it only provides an alternate explanation for the evidence.
It isn't actually hard to flesh this line of thought into a more compelling argument, but I think the accidental long-life thought experiment hits much harder.
Edit: Upon rereading, I had forgotten that Eliezer's version ends with a line that includes the thrust of the TheOtherDave's argument: "I think that if you took someone who was immortal, and asked them if they wanted to die for benefit X, they would say no."
(nods) Agreed; I don't think I was saying anything Eliezer wasn't, just building a slightly different intuition pump.
That said, the precise construction of the intuition pump can matter a lot for rhetorical purposes.
Mainstream culture entangles two separate ideas when it comes to death: first, that an agent's choices are more subject to skepticism than the consistently applied ground rules of existence (A1) and second, that death is better than life (A2).
A1 is a lot easier to support than A2, so in any scenario where life-extension is an agent's choice ...
Last Wednesday (2010 Dec 01), BBC Radio 4 broadcast a studio discussion on the question: "should we actively try to extend life itself?" The programme can be listened to from the BBC here for one week from broadcast, and is also being repeated tomorrow (Saturday Dec 04) at 22:15 BST. (ETA: not BST, GMT.)
All of the dreadful arguments for why death is good came out. For uninteresting reasons I missed a few minutes here and there, but in what I heard, not one of the speakers on any side of the question said anything like, "This is a no-brainer! Death is evil. Disease is evil. The less of both we have, the better. There is nothing good about death, at all, and all the arguments to the contrary are moral imbecility."
Instead, I heard people saying that work on life extension is disrespectful to the old, that to prolong life would be like prolonging an opera, which has a certain natural size and shape, that the old are wise, so if we make them physically young then old people won't be old, so they won't be wise. Whatever cockeyed argument you can construct by scattering into a Deeply Wise template the words "old", "young", "wise", "decrepit", "healthy", "natural", "unnatural", "boredom", "inevitable", "denial", I heard worse.
If I can bear to listen again to the whole thing just to check I didn't miss anything important, I may write something on their discussion board.