Indeed, put that way, everything could be sorted out.
This Uchiha Nobuhiko had worked for the Masked Man because, at some point—perhaps when he had fallen on hard times—he had been coerced by him. In any case, only after the Masked Man had found his weakness or obtained leverage over him had Uchiha Nobuhiko been forced to cooperate.
Yet neither side had ultimately been able to trust the other, so both had placed curse marks on each other.
The Masked Man feared that Uchiha Nobuhiko, whose strength surpassed his own, would cut corners or slack off. Thus, he had imposed the condition that Uchiha Nobuhiko could not brush off his orders. He had also tied the activation condition of Uchiha Nobuhiko's curse mark to his own heartbeat. If his heart stopped, Uchiha Nobuhiko would die as well, practically forcing him aboard the same ship.
Uchiha Nobuhiko likewise did not trust the Masked Man. That was why he had made the Masked Man place a conditional curse mark on himself as well, preventing him from deliberately sending Uchiha Nobuhiko to his death. It was a way to establish forced trust.
Now, for some reason, Uchiha Nobuhiko might truly have wanted to avoid provoking Konoha, or perhaps he had some other objective. That was why he wanted to break free of the Masked Man as soon as possible. At the same time, he might not have wanted the Masked Man to obtain the Nine-Tails and increase his strength, which was why he had chosen to make this deal.
And because of the curse mark's conditions, he had no choice but to fight for real. The various conditions he had set were quite carefully considered—they neither violated the conditions of his own curse mark nor prevented him from carrying out his plan.
Seen