Your hypothetical has nothing to do with quantum mechanics or many worlds, and everything to do with special relativity.
The hypothetical has nothing to do with quantum mechanics. It was obviously, and explicitly constructed to address the specific claim being replied to, using no set up more complex than physical movement. That claim being:
You should be able to justify any particular course of action without a metaphysical commitment to the reality of unobservable components of the universe's wave function.
It so happens that asr's reply indicates that our disagreement regarding how to make decisions when dealing with the implied invisible is not limited to quantum mechanical considerations but also applies in this simple case. (Based on that reply) we disagree both on how to make decisions in general and how to account for the implied invisible when making decisions, even when only very mildly unintuitive physics is in play. That being the case, knowing that we additionally disagree about how to handle the implied invisible when considering quantum mechanics is completely unremarkable.
If you'll notice, he explicitly uses the phrase "unobservable components of the universe's wavefunction", and the context is clearly many worlds quantum mechanics. This means your thought experiment is not at all analogous to his statement.
Your implied invisible (observer outside the light cone) is qualitatively very different then his implied invisible (unobservable components of the wavefunction). Your thought experiment shifts the focus by subtly redefining the original statement.
Today's post, Living in Many Worlds was originally published on 05 June 2008. A summary (taken from the LW wiki):
Discuss the post here (rather than in the comments to the original post).
This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was Why Quantum?, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.
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