This throne is called vyÄsÄsana, sitting place of VyÄsadeva. So one who is representative of VyÄsadeva, he can sit on this throne. So guru, by paramparÄ system, guru is seated on the vyÄsÄsana because he is the representative.
ÅrÄ«la PrabhupÄda's lecture on Bhagavad-gÄ«tÄ 2.16 -- London, August 22, 1973
