He's stubborn. His way or no way - humidifier drip or no drip at all.
Did he not give actual reasons, or did I miss them?
When one is confronted with facts but choses to ignore them, thats not stubborn or ignorance. At best it's irresponsible, however I personally would call it stupidity.
I would like to have him read this thread and have you post his response.
You seem like an intelligent well spoken young man.