Mule trait human only?

So I was probing around in the brick when I discovered that The Mule trait, unlike the brightmark, doesn’t have the restriction human only on it. Was that just a misprint, or does it mean, with the permission of the group, someone could play a Kerrn or even Mukhadish Psychologist?

Mule is a wacky exception anyway. Sure, if your group goes for it, you can play a Will 4 gangly troll mindreader.

The Mule is really meant to be human. But if you and your group are excited by other possibilties, I say go for it.