Obito was in no particular hurry to take Danzo's life.
Therefore, when he first ran into Danzo, he did not immediately use Kamui to snatch him away.
In his eyes, this old bastard had spent all these years doing so many despicable things under the guise of righteousness. Regardless of whether his ultimate goal was for the sake of Konohagakure or not, those deeds deserved to be brought to light.
Chapter 208