I don't think they employ him as a commentator/representative because he smokes, they employ him in spite of it.
He's an advocate of weed but he's professional enough never to bring it up in commentary. He expresses his pro-weed opinions when away from the UFC. Fair enough he's essentially representing the UFC but I don't think people care that much about weed in sport.
That's a good point actually. What happens if a Dutch fighter tests positive for 'cannabis metabolites'? It's perfectly legal in northern Holland (it's my understanding that they're more conservative the further south you go). If they had a show in northern Holland would it be OK?
Don't they regulate themselves using NSAC guidlines or something in other countries? If so will still get busted.