Obviously because noone gives a rats ass about Charlie Sheen nor was he at any point in MMA history ever considered G.O.A.T. There were times on HDNet where they had GSP ranked solidly behind Silva if not rank 2.
Silva has more title defenses than Weidman has fights. For the same reason Weidman doesn't want to fight Belcher Silva's camp doesn't want to fight Weidman.
Best Fighter on the planet.