The demon's pretty slimy. And, yes. The hourglass does have a certain amount of radiation-type damage. Except instead of cooking him, it corrupts, fouls everything it touches. The zombies are more of a "sepsis" risk as opposed to a "zombify" risk. And at severe risk of demon seduction or worse. Cause that, would break Dean, and the demon knows it.

I'm glad you're enjoying it! Thank you for the kind words.