I did not say he was an outsider, just that the ritual would likely not be "extremely beautiful" to one, according to Aumann. Certainly a day of rest is generally a good thing, few people disagree. But useful and beautiful are not at all the same thing. His argument, as quoted, was completely backwards from the usual ones ("you have to observe Sabbath if you are Jewish"): "Sabbath ritual is beautiful, but one must be religious to observe it, so I better be religious". Whether he really thought that or not, I do not know.
Just came across this interview with Robert Aumann. On pgs. 20-27 he describes why and how he believes in Orthodox Judaism. I don't really understand what he's saying. Key quote (I think):
Anybody have a clue what he means by all this? Do you think this is a valid way of looking at the world and/or religion? If not, how confident are you in your assertion? If you are very confident, on what basis do you think you have greatly out-thought Robert Aumann?
Please read the source (all 7 pages I referenced, rather than just the above quote), and think about it carefully before you answer. Robert Aumann is an absolutely brilliant man, a confirmed Bayesian, author of Aumann's Agreement Theorem, Nobel Prize winner, and founder / head of Hebrew University's Center for the Study of Rationality. Please don't strawman his arguments or simply dismiss them!