What Roy Talor and his team accomplished was a repeatable, scientifically valid study protocol that has demonstrated that there is a direct link between the adipose/hepatic fat in the body and Insulin Resistance. They also established that this level of fat can be effectively removed by following an ultra-low calorie-restricted (starvation) diet. From this, it has been postulated that this was a cure for diabetes.
Unfortunately, not all obese people have diabetes or insulin resistance. Secondly, not all T2 diabetics are obese or have IR caused by adipose fat, and there are other causes of IR it would seem. So it worked for some (46% from memory) but not all the participants. Lastly, this forum has a lot of anecdotal evidence that the effects of the diet wear off in time, and like most calorie reducing diets, need to be repeated like a yo-yo. Those that succeed in maintaining remission seem to follow some form of follow-on diet to keep their condition in check. Similarly, there is quite a lot of anecdotal evidence that carb restriction has as much effect, and appears to be a more sustainable way of life.
IMHO Roy Taylor has made an important contribution to the treatment of diabetes but has not found the golden bullet. His is only one pathway to Shangri-la, and there are others. He offers another useful (evidence-based) tool that the NHS can offer to diabetics. But Low Carb is also NHS adopted as a treatment method, but not as a way of life, The LC training course offered on this website is also available 'on scrip' and the work on LC by Dr David Unwin has also be recognised as valid, although there has been a technical issue over some of the infographics he used.