In light of some later comment-threads on related subjects, and in the absence of any direct explanations, I tentatively (20-40% confidence) conclude that the attitude is that the process that generates the code that extracts the CEV that implements the FAI has to be perfect, in order to ensure that the FAI is perfect, which is important because even an epsilon deviation from perfection multiplied by the potential utility of a perfect FAI represents a huge disutility that might leave us vomiting happily on the sands of Mars.
And since testing is not a reliable process for achieving perfection, merely for reducing defects to epsilon, it seems to follow that testing simply isn't relevant. We don't test the CEV-generator, by this view; rather we develop it in such a way that we know it's correct.
And once we've done that, we should be more willing to trust the CEV-generator's view of what we really want than our own view (which is demonstrably unreliable).
So if it turns out to involve wearing watermelons on our feet (or living gender-segregated lives on different planets, or whatever it turns out to be) we should accept that that really is our extrapolated volition, and be grateful, even if our immediate emotional reaction is confusion, disgust, or dismay.
I hasten to add that I'm not supporting this view, just trying to understand it.
Taken from some old comments of mine that never did get a satisfactory answer.
1) One of the justifications for CEV was that extrapolating from an American in the 21st century and from Archimedes of Syracuse should give similar results. This seems to assume that change in human values over time is mostly "progress" rather than drift. Do we have any evidence for that, except saying that our modern values are "good" according to themselves, so whatever historical process led to them must have been "progress"?
2) How can anyone sincerely want to build an AI that fulfills anything except their own current, personal volition? If Eliezer wants the the AI to look at humanity and infer its best wishes for the future, why can't he task it with looking at himself and inferring his best idea to fulfill humanity's wishes? Why must this particular thing be spelled out in a document like CEV and not left to the mysterious magic of "intelligence", and what other such things are there?