Let's face it, that was actually a pretty smart plan.
It was still dumb he didn't heal that one girl, but that would mean removing his motivation to avenge her, which I think follows his insane logic/moral code?
But otherwise, he knows that Freya has a lot of ethos and her word is basically divine in their eyes, so it's a given a large majority of the guards, who consider her word scared, even more so than the peasant, would defect or be overwhelmed, forcing Norn to either fight a battle she would know she would lose, or tactically retreat as to avoid it. Plus the fact he could sneak up as a guard and probably not be noticed because of the confusion at the time would be great, as well as removing Hawkeye's benefit of being a long range fighter.
Game was rigged from the start, kid.