Marmahu, I always read your posts with interest. It puzzles me just as much as you why some children respond to the gf/cf diet and heavy metal detox protocols and others don't. I get the sense you have read a great deal in your parenting journey and done a lot of your own soul searching.
When my son was first diagnosed almost three years ago I happened upon Dr. Amy Yasko's work on metabolic pathways. If you google her a great deal of info comes up. Since she is a biochemist a great deal of what she writes has too much scientific jargon for me, but, I splurged and bought her book. I slogged through it, and it confirmed in my mind that there are different "pathways" of body detox that are blocked or partially blocked in different people with the same diagnosis. While she suggests testing a person's blood for deficiencies and genetic markers to determine what pathways to work on to help relieve symptoms, you can, as I did, use trial an error. I tried B-12, it worked. I tried the diet...it worked....but, if it didn't, I would have kept trying.
I know you've seen for young son that it all worked out in the end, where he had maturity, good parenting and many of his symptoms resolved. But, I'd also hate for people to think that that is automatically going to happen without helping and supporting that biomedically. I've seen it go the other way, where kids take a nose dive, around 11/12 (I'm a little worried about that myself....my son is doing so well, i'd hate to see that change :( )
I think it's interesting stuff, the newer work that's coming out by Yasko and like Dr. Walsh above. If a child is very symptomatic, I know you can relate to this...a parent usually sees something very unhealthy is happening in the body. The bowels aren't working right, there are chronic immune problems etc. Autism is just a part of the picture, often.
It's possible Young son, may have been doing intrinsically what he needed at the time, by eating a limited broth diet....I wonder about that when you've mentioned it before. It may have helped his body detox, which, in my son's experience with it, can take quite a while to even see real lasting change in behavior and mood which may be why you didn't link it to his eventual improvements....Just a wondering on my part....
I just thought I'd chime in in this regard. I hope you don't mind. I respect your contributions and hope that my son turns out as well as yours :)