They finally did an experiment to properly establish if his blood can cure zombieism, yet after confirming it they still aren't thinking about whether people he's cured gain his other attributes. Do zombies start ignoring them? Does their blood become curative? Do they gain super-strength and healing factor? It's an obvious option, and would completely take the focus off Yihwan. All he'd have to do is cure people along the way, then tell those people how to cure others, creating an exponentially multiplying wave of zombie cure, spreading in all directions at the speed of
people.
I guess the story would end too quickly if they were smart enough to think of that
