Still feels like that guy is actually serious. What a bizarre character.
I think that might be the point. He's not so much "evil" as he is entirely amoral and he wants to accomplish something good/useful but he doesn't care how he gets there and thinks nothing of killing the zombie guinea pigs he uses or the pain and harm he causes to those connected by the zombies when they go feral.
It's like if his cure doesn't work and the government rounds up the zombies and kills them all, problem solved. If it works then the zombies are reverted, problem solved. And if it doesn't work then he only killed a zombie so who cares and he can move on to his next step/attempt. In any situation he's serious about helping humans because his end goal is to stop the zombie menace and how they get there is irrelevant.
We just needed to see the shadowy framing and the evil eyes and wicked smile and all that early on to understand that his badness is not because he's enjoying the pain he causes but because he aggressively doesn't care and that apathy/indifference is what makes him bad.
Or I'm just reading too much into it, lol.