It means that even the Tokugawa shogun family, who eclipsed Imperial Court's authority, exerted control over Imperial Court by the "Kinchu narabini kuge shohatto" (a set of regulations that applied to the emperor and the Kyoto nobles) etc., and gained the structure of 'kogi' (shogunate) and the position of 'feudal king,' had to rely on the appointment by the Emperor in order to legitimate their dominion.
これは朝廷の権威が失墜して、禁中並公家諸法度などによって朝廷にすら支配権を及ぼして「公儀」の体制と「封建王」的な地位を獲得した徳川将軍家でさえ、その支配の正統性は天皇による将軍宣下に依存しなければならなかったことを意味する。