Not a very Dustbringer thing, to me. (I'm still in the "Ash will become a Dustbringer camp.") Good person thing is debatable, because as you said, 4.5 millenia will change people, good or not. The rest of the Heralds, no doubt, started as good people that wanted to protect their people and you saw what happened to them. Taln is, as acknowledged within the books, a very nearly archetypal Stoneward: dependable and strong. There is no one better suited to outlasting that time and the torture that came with it than him.