He had no control over his body. When the Jutsu is cancelled, the Edos had time to move around freely for a little while. Thats why Madara could do them.so as I understand that if the one who was summoned knows how to release the technique, along with the seals necessary, he can break out of the command.
this is what I understood from the speech. I wish we had better translation.
madara:
there is a risk to ET. if you know the seals you can release ET's contract. this is really dangerous (for the user, in other words kabuto in this situation). (because the user, in other words kabuto, will have to face) an undying enemy with unlimited chakra.
tell kabuto that he shouldn't use forbidden techniques carelessly.
if what I understood is true, and that's the deal why didn't tobirama break the seal off when he was summoned by orochimaru? because he was completely turned into a mindless-puppet?
The 2nd Hokage was sealed, so therefor he couldn't move at all. If the jutsu was cancelled, then he could do the handseals and show his brother as well.