In my opinion applied behavioral analysis is not an ethical treatment of autism, the reason I think that is as follows.
Stimming is by nature a coping mechanism, that is used to deal with stress, ABA punishes autistic people for relying on stimming as a way to cope with stress, it does not address the stress which is the cause of the stimming. So while the stimming may be gone the stress that is causing the autistic person emotional pain is still prestent however they now don't have a coping mechanism to deal with that stress which is causing them emotional pain. The only way I can see to ethically deal with stimming such is to remove the stress which is causing the emotional pain, provide support for the autistic person and keep giving them outside stimulation so they do not feel the need to stim.