Actually, remember that Tobirama had been physically ripped apart (or at least his clone was) and then he nuked himself (or at least his clone did). He never came under the attack of the black stuff. The same goes with Minato, he only came under the subject of the black stuff very recently.
Edit: Correction, Tobirama (or at least his clone) did come under the black stuff before; however, this does open up to something I hadn't considered before, which is the difference between Obito's skill now and Juubito's skill. Before the black stuff was defined as a nature transformation of more than three elements, but now we see the inclusion of Omnyōton, which "erases all Ninjutsu". I think it has a lot to do with his control after all, as he was still wary of attacks before.