Bear with me here, I am bit of a N00b too.
The scenario might be different than a random game in that Gnarri is a story line NPC.
In other words once he joined you, he can't be gotten rid of....
If left clicking on him in army window then right clicking an open tile when he has movement to make that tile doesn't work, then...he's shackled to ya for the duration..the ol' ball and chain!
Maybe some guru will confirm or deny this I really do not know...
