I'm going to say this once more. It is unlikely that Guan Yu is naive. The main reasoning for this is simple. If there was only town and mafia factions in this game, yes the cop could be naive and the game would not be one sided. However with a cult as well, the town would be at an extreme disadvantage if they had only a naive cop. They would have 2 cops, one naive one proper to put them on an even footing with the other faction. We, however do not have 2 cops. The logical reasoning is that the cop is legit as are his investigation results.