I have coeliac disease, been diagnosed 15 years now. I am glad this issue is getting noticed. I have not been able to get gf food on prescription for over 10 years. I suspect if I asked my GP now they'd look at me as if I had two heads.
For someone like me who is well versed with a gluten free diet, has a decent kitchen with an oven, microwave, hob and a working fridge and money to pay energy bills, having to survive off naturally gluten free foods wouldn't be an issue.
But food bank users may not have access to these things. Rice and potatoes are usually fine as long as someone has access to a hob and kettle. The main issue is food to have "on the go". I can heat leftovers in the microwave at work for lunch but not everyone has those facilities at work. So that's when convenience foods like bread etc come in so they can make a sandwich.
You might be surprised that compliance to a gluten free diet is said to be between 40-90% however there is no real way of measuring this unless people are assessed via clinics or GP regularly. Some GP practices call in coeliac patients to be tested every year but I have not been tested since 2017 - I suspect partly because I do comply with the diet so they don't see a need to follow up.
But I can understand coeliac sufferers who do not have severe symptoms when eating gluten (unlike me) may be tempted to consume "normal" foods particularly if they are recently diagnosed, don't have many cooking skills or are struggling with the cost.
Another issue is children with coeliac disease - much more likely to be fussy eaters, teenagers in particular may rebel, parents may just want their kids to eat something and packed lunches without bread products are tricky.
I hope that food bank users who have coeliac disease are provided with some pasta / bread etc, if products themselves are not donated then bought with monetary donations. However in practise I suspect many users stick to naturally gluten free foods, go hungry, or eat normal food. The latter choice can lead to long term health issues.