Petunia,
I laughed so hard at the description of your son reading a book with one hand while practicing with another. I well remember trying to hide a Zane Grey novel behind my music so I had something interesting to do while waiting for my hour of practice to tick off of the egg timer.
Your comment about his superior rankings at festivals also reminded me of my own experience. I was musically talented, and if I could hear my teacher play the piece first, I could mimic her within a couple of weeks without ever really learning to read the music, I earned unanimous superiors at our state festivals every year but one - when I walked into the concert hall and had my mind go completely blank where I didn't even know where to start on the keyboard. Once I was given the first note, it all came back, and I ended up with superiors from two of the three judges.
I tell you this by way of underlining my own experience when I say that talent does not mean love or passion for something. My sister loved piano and was far more passionate and disciplined about practicing. My mother wouldn't let me quit, so I started devising every way I could think of to practice but not excel, etc. I have my great grandmother's piano in my home but never touch it except to dust it.
If he is actively sabotaging himself, maybe he is sick of piano but doesn't know how to express it appropriately - or he may not even know how to recognize that he is burned out.. Maybe it is time to recommend a break from lessons and to suggest that he take some time to think about whether he is ready to move on to a different instrument, would rather just play the piano for his own enjoyment, etc. Perhaps an enforced sabbatical from lessons will make it the forbidden fruit where he realizes he does want to take lessons again and put his genuine best effort into it.
But you, of course, know your kiddo. This is just my totally biased perspective.
