We know that there are civics which require Militarist, but they're not visible to Wiz when he's selecting his third civic. Therefore we can be pretty sure that once you get into the game you're only being shown the choices you have available to you at that very moment.Isn't it the case only for hivemind civics? Usual civics seem to be just grayed out if ethics don't match.
I guess they could all be tucked at the bottom, but there are a lot of ethics that Wiz doesn't have (five), so I doubt they could all fit down there.