Kevin is not a bad person! If you just go back and listen to him and what he says, he sounds generally like a nice guy. He worries about desert bluffs just as much as cecil worries about nightvale. Sure the place where he comes from is different to what we're used to, and I think cecil's prejudice against desert bluffs has seeped into most of us as his audience, but if you really think about it, he has never expressed any desire to hurt cecil or anyone else. Sorry this is a longish answer but it's just something I've been thinking about more recently: neither cecil nor kevin can condone killing or harming your doubles. In the portal, when the two of them met, it was cecil who reacted so strongly to kevin and started to attack him, but both of them backed down after and just left. argh, again sorry about this i guess what I am trying to say is that I can see kevin being concerned about Cecil's face as a thing that would happen and make sense.
I honestly think Strex tortures their workers into believing in a smiling god, and to hurt others. When they get the job done, they snap back to themselves, and that's when if they worry about stuff like that, they try to fix it, not realizing what they did.