DLA reduced from higher to lower as now adult

Our son,has just turned 16, his DLA award has been reduced from higher rate care to lower and lower rate mobility for supervision stopped.He has very severe widespread eczema and very severe multiple food/environmental allergies.Told on phone (waiting for written reasons) given that he is now an adult he can now apply own numerous creams and bandages self, albeit slowly.
Given severity of condition, number of creams to be applied over entire body, bandages soaked in bath prior to removal as adhere to skin with blood and oozing infection sites and reapplied min 3-4 x daily ( taking around 50 min each bath) as expediently as possible as itching so intense he is unable to control the urge to to rip his fragile skin thus ensuring not exposed for longer than absolutely necessary. He still requires constant supervision to alert to scratching, support to resist and treatments administered. He also requires attention in this regard throughout the night and watching over till he falls asleep. All of this is vital to prevent serious damage to skin. He cannot do this himself! He also has very serious life threatening allergies to traces of numerous substances. The decision maker concluded that he may feel reassured but the supervision was not necessary, despite fact, as stated in form, he has a one-to-one trained adult with him all time in school to observe and intervene for reactions and administer any treatment required.
Is this typical that on becoming an 'adult' you are expected to undertake such treatment yourself even if this would certainly result in a serious deterioration of the condition? We are still in a state of shock at the decision.