I see it similarly to how
@Inka has described it. The cells store excess glucose as fat and once they reach a certain limit, they don't want to accept any more... this may be the "personal fat threshold" that Professor Taylor talks about.
This academic article by Prof Taylor, from 2021, gives a good overview of his work, including the idea of the 'personal fat threshold':
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8247294/ .
From this and other academic articles, I gather the idea is as follows:
Subcutaneous fat does not cause Type 2; but each of us only has so much subcutaneous fat capacity. Picture it as a bucket; some people have a huge bucket, others only have a small bucket. People get T2 when their own personal bucket spills over! Because, once your body starts storing a lot of fat in and around your liver and pancreas, rather than subcutaneously-- that's when you get T2.
Take two people, Ann and Bill. They both start off with a BMI of 22. Then both of them start eating too much and being very sedentary, so they both start gaining weight in the form of fat.
Ann has a HUGE amount of subcutaneous fat capacity. She becomes vastly, morbidly obese, and still doesn't get Type 2-- because her body continues to store more and more fat subcutaneously and doesn't store it as 'ectopic' or 'visceral' fat, fat in and around the liver and pancreas. She will have a lot of other health problems, but not T2.
Bill, however, has very little subcutaneous fat capacity. So his body very quickly starts storing fat in and around his liver and pancreas-- his small bucket overflows into the bad places very quickly. So, by the time Bill's BMI is 23, he has T2.
This would explain why many obese people don't develop T2, whereas some people with BMIs of 23-25-- which is not even classed as overweight, let alone obese, in official terms-- do develop T2. (Note however that it seems to be very rare for people with a BMI under 22 to get T2.)
Very low calorie diets work because, with severe calorie restriction, your body 'eats' ectopic or visceral fat first, before it starts 'eating' subcutaneous fat. So people who are obese and have T2 may remain obese yet still reverse their T2, because they've lost their ectopic fat.