No, they don't need to be 100% on the same page, that seems like impossible anyways as they are not robots. Directors have a vision where they want to take the game, then it is up to individuals to do their interpration of that vision. It is not open revolt, it is humans doing art, design or writing. There is no way, everything that Boyarsky intents for the game will be shared and done in exactly they way Boayrsky intents it to be, by everyone in the 80-120 team members who have worked on the game.
It is teamwork and the Leads and Project Director should be able to see if everyone is on the same page (or near enough) when it comes to actual content that makes into the game. Writing and art can be interpreted in multiple ways, so even if some artist/writer views his/her piece of art/writing expressing something, it doesn't mean everyone will pick up on that and will see it the same way. Someone might put a bit more emphasis on something that they create but in the end Boyarsky, Cain and the Leads will check whether it will stay true when compared to the rest of the game. So someone won't go totally overboard with their own ideologies in the game.
They are talking about ideologies, not that someone is making a 3rd person game when the game is 1st person and since games are seen as art, they can be interpreted in multiple ways.