While I agree that Tobirama is only bound by his own technique due to Orochimaru utilizing Hashirama's DNA within him, the same thing could most likely be said about Hiruzen and Minato. Hiruzen had extensive knowledge of the Edo Tensei, knowing that the technique wouldn't disperse even if he killed Orochimaru and despite summoning Minato failed due to his sealing within the Shinigami, Hiruzen attempted use some type of jutsu to prevent Minato from being unleashed, hinting at the possibility of him being able to break the control; it's completely possible, seeing as his sensei was the creator of the technique.
Likewise, Minato was taught a variety of fuinjutsu by Kushina, including Shiki Fujin. I'm sure he has something in his arsenal that could have undid the control before being completely bound. If not, going into his completed chakra cloak form probably would have broken the chakra hold on him. Of course, this is just an assumption.