Although much younger, we ran into the same issue with DS. He's a perfectionist and any criticism of his work, especially writing, is probably going to be taken personally. (WWE became a problem for us because of this)
I'm now trying some of the ideas from BW Writer's Jungle with great success. I'm still reading her book, but it sounds like the idea is what the previous poster mentioned. She has the book divided into sections to help break down the process of writing, revising, editing, and publishing. Each step is then broken down further for the parent to give clear directions to help the student.