Because I'm a very stubborn person I've spent waaaaay to long on it and might have a solution (which is still not exactly 100% foolproof I guess).
Seems like your approval with him must be just right for that scene to trigger (somewhere in medium-high range) and I might be wrong but you shouldn't progress too far into the main story - for some reason I can't get it on one of my saves where I've already spoken to Kahga and Nettie).
Yeah i can debunk that, i got the scene after talking to Kahga and Nettie, with Exceptional approval, and rather late in the story (basically right before i decided to kill the goblin leaders).
It is very random.
