Cargo carried by the NPCs is based purely on lore and who creates the product, not based on player-made laws. This is because the mod is used on several servers, and some player factions on those servers, and our own, might or might not make certain goods "illegal" in their house/territory. And not every new leader views laws the same as the last, so player laws are very fluid. NPC faction lore is not quite as fluid, and thus a much better thing to base NPC cargo on.
Lore-wise, Synth Weed is not universal contraband, and thus Cryer can transport it, since they create it. Not like Cryer players are gonna get FR5'd for what NPCs are carrying.