well yeah I have tried all possible combination:
Human BST
Barbarian BST
Barbarian Monk
So I can see how its limited to a race (just like dwarves don't have robes), but its also limited by a class. Even for NPC - npc human monk would show up in GI armor, but any other human npc, including monk GMs will not.
Too bad... I wanted to make some Human BST in Wu's