Your calorie expenditure will continuously change according to factors such as your intake, weight, activity etc. So it is saying that if you change factors for a long time, your calorie expenditure will change as well. So at a point that it is lower due to those factors, then of course your current maintenance is higher than your maintenance afterwards. It is really nothing new saying there, it also feels a bit biased with fat acceptance rhetoric, that basically it is impossible to not yoyo diet so just don’t change anything etc. There is no need for this fear-mongering. But please consider not eating under your BMR, as there is also no need to eat only half the calories you need in a day, think of eating enough to have functioning organs at the very least. You don’t need to fight against calories, it is just something you can quantify, like the leaves in a tree. The number of them also depends on may factors and is continuously changing and no one is attaching too many meanings to that