We give careful thought to every YPP application and each one needs to be manually reviewed by our team of specialists. Due to the high applicant volume, it’s taken us a while to review every channel. We’ve been sharing updates about this here: https://goo.gl/d2c2y9
give him the reason why you disabled his monitzation! you were the one that did disabled it, so you should know what the reason is! You can’t just direct him to a list of the possible reasons why it happened, you have to explain how to fix it! and maybe even why you did it!