The cure was located and Zain needed to figure out what to do. What was the best option? Using it now would better the situation in the city. Perhaps, because there would no longer be any zombies, then the armies from the outside could move in.
They could always meet with General Begal and maybe hand him the cure. That would then mean putting trust in someone else's hand though. There were also the words of Humfree that humans weren't strong enough.
This was a group of demons that had taken over countless other planets before. Were they only being suppressed now because of the high stage zombies in the middle of the city? If they were all to disappear, would that allow the demons to spread out?
There was also the thought of what would happen to them as well. What did cure even mean, did it mean that all of them would die? Would the large Titan zombies really revert back, as well as the higher stage zombies that were gigantic in size and no longer looked human?