(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 the arguments against life-extension will tend to rest heavily on A1.
Setting up a scenario where A1 and A2 point in different directions -- where life-extension just happens, and death is a deliberate choice -- kicks that particular leg out from under the argument, and forces people to actually defend A2. (Which, to be fair, some people will proceed to do... but others will balk. And there are A3..An's that I'm ignoring here.)
The "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." argument does something similar: it also makes life the default, and death a choice.
In some ways it's an even better pump: my version still has an agent responsible for life-extension, even if it's accidental. OTOH, in some ways it's worse: telling a story about how the immortal person got that way makes the narrative easier to swallow.
(Incidentally, this suggests that a revision involving a large-scale mutation rather than a rogue scientist might work even better, though the connotations of "mutation" impose their own difficulties.)
It might just be easiest to postulate an immortal person and obfuscate the process entirely.
Also, I am trying to come up with a quick test to distinguish passive deathists from active deathists - ie, who would refuse an offered immortality potion, and who would vote against funding to develop an immortality potion? Who would say "I don't want to live forever" and who would say "People shouldn't live forever"? Arguments need to be tailored in different ways for these different types. Something like "How about you take the potion, a...
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.