DR Elmore, it's indeed disappointing that Jeremy hasn't yet replied to you about illustrating the book.
Rightly or wrongly, my first thought (when you said he didn't reply at all, not that he replied but said no thanks) is that many MANY otherwise good people are surprisingly slow, or just downright poor, at responding to things like email in a timely manner. Or they're simply disorganized in that way while being expertly on top of things in others -- which Jeremy obviously must be in his musical life. I've had nothing but the best impression of those Claytons -- though other than "knowing him" through your posts and stories about him, I've only had the pleasure of chatting with Josh a couple of brief times. Those illustrations were amazing and it would be so great if he can give this some serious thought.