I would think that the Sony 600, which is a touch screen, would be great for him. I'm not sure how severe his CV, but if it's really difficult for him to hold you could mount it somehow on one of those lap tables, so he could just lie down (or sit) and it can be angled easily so he doesn't have to hold it. Then, all he has to do is swipe a finger across the Reader to turn the page
Hope this helps!