it may have worked out in Mo's favor to have the coaching change. I loved the way that Bronco helped Ziggy go from complete ignorance of the sport, to now being one of the top D players in the NFL. He didn't push him too fast, and he was able to connect with him in a way that goes beyond football.
I think that the same could be done with Mo, but at an even faster pace, because of the common language. If needed, instructions could be given in Tongan, by both coaches and many of his teammates. It is a dynamic that is incredibly rare, and could open up a new pipeline for recruiting if successful. These coaches know the Tongan culture, know how to relate to him, and there really are no barriers.