Is not the leader of the Shirai Ryu nor the lord of the Beyul. The Sect itself is a meritocracy and the Beyul doesn't understand land ownership.
It is said that there is a Gateway to Shambhala hidden somewhere within Rigzin Namsum.
His actual role within the Shirai Ryu is that of 'The Shatterer'. Master of the Dragon's Pulse and one of the techniques passed by the Vidyadharas. He is responsible for removing stagnation and malfunction within the sect.
The monks that were spared from his purge are the de facto spiritual leaders of the whole beyul and the main attraction of the location.