I think this paper is overly exoticizing AI. People have always been externalizing deliberation to others, be they parents, friends, bosses, partners, gods, spirits, journalists, advertisers, superstitions, tarot cards, or rubber ducks.
Perhaps it is worth calling all of these "system 3", but I see no reason to separate LLMs from them. Our judgment has never been our own entirely, and even if there is nobody else to defer to we can defer to "what they would do".
We accept that these external sources are flawed and can give us bad advice that we follow, but we keep listening as long as we think that is made up for by good advice or other factors.