Something funny is going on with people's moral reasoning here and I suspect it isn't peculiar to rationalists, but reflective of something in wider culture.
Maybe it is peculiar to rationalists, or I should say, "rationalists": people who think they're rationalists. Quarantining people with colds and not quarantining people returning from places with Ebola have this in common: it is the opposite of the practice seen in the wider world. Therefore, if you take this view, and assemble clever arguments for it, you must be being more rational.
Source.
Moving my commentary to a separate comment, so as to disambiguate votes on my commentary and the original argument.