pebblerocker commented on the non-spoiler post that "trained linguists listening to [Ian Bretano's] first conversations would have had a better starting point than a biologist, assuming the ship had anyone interested in languages, which isn't a given."

Taylor's Children knew about the atevi, right? I know they were trained to be super-polyglots because of linguistic drift between the ship-humans and the Mospheirans, and I know in Book 2 we find out that at least part of the reason for the Guild opposing the landings was the existence of an intelligent indigenous species, but I don't know whether there were already linguists. ISTM there might not have been, meaning Ian might really have been the best suited for the job!