Teal'c had a rather unique experience as a Jaffa, serving two Gods, aware that his father died unjustly, trained by Bra'tak to question the other. He wasn't blindly following orders in as innocent a way as a lot of other Jaffa were. It's like finding religion--once you find a truth, you have to then act on it, and Teal'c continued living a lie. I would think that would have a huge impact.

He's also blazing trails in a new culture and society. I think that would get tiring.

And, I would argue that he speaks up when it's warranted. This guy commanded *millions* and he is perfectly capable of judging and acting and being that guy if he needs to. I suspect that he doesn't want to, and is enjoying letting someone else lead.