It didn't seem to be overly negative to me, but definitely negative and overly cautious. I find it disheartening that an objection to recommending it to people is that it might be difficult for people to follow. There's a similar mind set with respect to LCHF. In my opinion, giving advice that works but maybe people won't follow is better than giving people advice that they will follow but doesn't work. There is no advice that will work well for unmotivated people.
The writers say the ND wasn't compared to any other treatment, but presumably they had been following the standard NHS advice for possibly years without normalizing their blood glucose. 12 out of 30 normalized their blood glucose levels is obviously a massive improvement over the standard treatment, where virtually nobody ever achieves normal blood glucose levels without or without meds. The writers of the story could have pointed out.
I also found the link at the end to their advice on losing weight quite entertaining. They seem to think eating lots of carbs and fibre, little fat, and lots of exercise will work for weight loss, despite lots of studies that show this is not the best approach. Do they really think people find it easy to do that?