Unfortunately, people on iZombie have always been as smart (or dumb) as the plot demands. Ravi and Liv didn't know about the zombie army, but they knew that Martin lied about becoming a zombie from the fake vaccine.
I guess his plan is to turn zombies all over the country / world so they can't just bomb them out of existence. But he also seems to think that zombies are the next step in human evolution. The small flaw there is that a zombie needs about 12 humans worth of brains every year (going by Blaine's monthly extortion plan). Even if they could force humanity to donate every corpse brain to zombie kind, if they became more than 0.001% of the population, they'd run out of their food source.
Candy got screwed (literally) into becoming a zombie. Then she had to be a zombie hooker. Plus, she's missing part of her hands, I think. Yeah, it was about time for her luck to turn around. It's kind of funny. Who took the zombie cure who didn't become a zombie again or die? I can think of Candy and the girlfriend of the prankster kid in "Death Moves Pretty Fast."
Three episodes left. I'm guessing zombie cure gets created again next week.