I've re-read this post (read while on the road yesterday), and now I'm not sure what it's referring to - a 6x6 treated post that is twisted by an inch, or just bowed along it's length by an inch?
Constraining the two ends and pulling the bow out and letting it dry more like that will likely take some of the bow out, but I would think trying to untwist a timber would end up splitting it?