The Attack on the Salt Merchant Was a Cover
Denth did dozens of things like this, subtle methods of bringing the two kingdoms closer to war. This is the only one that Vivenna and Vasher figure out soon enough to be able to counter.
In this scene, Vivenna's chapter arc is her struggle with deciding when to make judgments and when not to. It seems that in our society, it's taboo to judge someone. If you judge, you're seen as intolerant. And most of us hate being labeled that way. I remember seeing an advertisement online just a few days ago that said something like "Please teach your children tolerance; teach them not to judge others."
Now, those who read my blog know that I'm big on trying to understand other people's viewpoints. I don't like how harsh our dialogues about charged issues tend to be. I've said I'm a peacemaker by temperament. However, I think telling someone, "Don't judge others" is just plain ridiculous. (Of course, maybe it's all just semantics.)
We have to judge. We do it every day. We decide who we want to be friends with. We judge which candidates we want to vote for. We judge which activities we want to be a part of. A lot of these judgments are influenced by our thoughts on the people involved in them.
It's not good to be racist. Skin color is a terrible reason to judge someone. But that doesn't mean that you shouldn't sometimes make judgments about people for other reasons. I think maybe we've become hypersensitive to this sort of thing.