Note that it says only from "orcs, kobolds, goblins, bugbears, gnolls, and hobgoblins", and notice that when you consider Vrudish that "Your best guess is that he is a troll.".

Demandtribute doesn't work on trolls.

If you look at Vrudish, it is apparently the intent he be considered a troll.

So I'm marking this as working as intended.