Sure, there could be health benefits to avoiding gluten, and maybe more study would reveal that. But the best science we have to date doesn't suggest that. If it does at some point in the future then I would be one of the first on that bus for sure.
At this point gluten is just one of the more popular "buzz terms" out there aside from those with significant health issues.
I do think that it is dangerous to take it a step farther and make any connections between autism and gluten when this has been studied and found to have no significant connection.
There is a reason why simply feeling better is not a good way to judge the efficacy of something.
A parent starts to phase out gluten from their child's diet and over the course of 6 months finds that their child is showing a noticeable difference. They attribute this to the diet change.
On the surface this seems great, however without controls in place there is no way of actually knowing why this child felt better. Maybe it was something in a particular food unrelated to gluten. Maybe it was a lifestyle change that went along with the diet. Maybe it was a gradual improvement in the child due to simply getting older and having better coping mechanisms (quite common actually!). There are all sorts of things that could be true but because there are no controls in place the parents makes claims that gluten-free was the answer.
Now there is an added burden for the parent of juggling dietary restrictions that might not even be needed, along with everything else that have to deal with on a daily basis.
These things are tricky but I believe offering good health advice to individuals is an incredibly important matter that needs to be handled correctly and with the best evidence we have available. Making claims that are completely factually incorrect (such as the autism link for one, but there were others) is doing a disservice to those who might be reading.
I KNOW that wasn't your intent, but I would simply encourage you to take some of the claims made in the things you linked and examine them in light of the actual evidence that exists. That's your way of doing things in areas that are hockey related (your article on Semin comes to mind for me) and I think you could do an even better job in the area of personal fitness and health as well (you already do good stuff there).
This is one area that I care a lot about since my wife works with individuals who have autism (among others) and we see parents making desperate attempts at changing things that cannot be changed, rather than spending their efforts in areas that are proven to work. Things like avoiding vaccines and spending time/money on gluten free diets are not helping their kids and actually have the potential to do harm. The least we can do is point them in the direction of sound science and avoid scaring them with things that are not true.