I think there are a number of reasons Coach may have performed for the viewers, if that's what he's doing. He may want to absolve himself of backstabbing Brandon by being able to claim God told him to do it, which some people, including Brandon, might accept. He may want to look better to the jurors, presuming they'd buy that he did what God was telling him to do, so he has to keep up the act for everyone, including the viewers. Or he just simply really, really wants to be thought of as this great leader with integrity and honesty. That seems to be really important to him, hence his references to himself as Coach and Dragonslayer. It may even have be the catalyst (or part of it) for him to become a minister. If that's important to him, it may matter to him that the viewers think of him as someone who gets direct instructions from God as opposed to someone who simply does what's best for his own game.
I didn't like Boston Rob in any of his seasons, particularly the last one, because he seemed to take such great pleasure in making others look foolish, even when it didn't make a difference in his game (e.g. convincing everyone to name the merged tribe after one of his wife's stuffed animals, just so the two of them could laugh about it). I was also just opposed to turning loose experienced players with a bunch of newbies. Dont like it this season either. I dislike Coach's tactics for different reasons that I disliked Rob's, however. Coach doesn't seem to take any particular pleasure in making people look stupid, but he does try to pretend that he's playing this tremendously ethical, honest game that matches his professed Biblically-based principles, when that's clearly not the case. Rob got by on his supposed charms. Coach is trying to get by on his supposed integrity. I guess I just don't like people who try to slyly manipulate other people without seeming to feel the least bit of remorse about it. I know it's part of the game, but we have seen people feel like crap when they've blindsided someone or apologized later when they felt as if they'd been particularly mean-spirited to someone. I guess if you're going to lie and cheat and laugh at people behind their backs, I'd rather you either felt some guilt about it or presented yourself as someone wholly nasty from the get-go, like Johnny Fairplay. Just don't try to pretend you're justified in behaving crassly for the sake of your family or because God told you to do it.