As a reader, and someone who hoped to start playing the game, I read this a while back and chuckled to myself about how all thieves steal from all npcs.
Now that I have played the game, and started DM'ing my own, I realize I was too naive.
Two new players joined last session, dropping in the middle of a dungeon (having followed behind the vanguard group not knowing they were there) and the first thing that happened was that the monk tried pickpocketing one of the players.
*facepalm*

I think the GM created that NPC specifically with Nami's stealing habits in mind.