I replayed the celebration multiple times and I just cant get it....did you do the fair thing with him before this? Since i dont know how to do that part either.....
Well i did met him in the fair but lose in the wrestling match. On nightmare 2 i got best ending i guess (rhot did talk to me after that quest so i think it's best ending?) And i gave the green gem back to roushk, also because rhot was there at the end maybe you need to have 1 heart with him, maybe. I don't know if any of these will help but as far as interaction with lizard tribe goes, these are the things that i did