Q. wrote: The opinions contradict the neuroscience which "demonstrates that an individual’s predisposition to become addicted to stimulant drugs may be mediated by brain abnormalities linked to impaired self-control".
This issue of whether brain abnormalities may impair self-control and awareness of consequences is not a simple matter. Neither is it always possible to be sure whether such abnormalities are actually there or not.
For example, going back to the 1970s, I had dealings with a guy in one of the psych hospitals in Adelaide who at 16 had gotten off a charge of murdering his Aunt and Uncle, who had raised him from and early age, to inherit their property. Two senior Psychiatrists in the SA public service had assessed him as not having a psychiatric condition that impaired him beyond Sociopathic personality disorder and as being responsible for his decisions and actions. However, his lawyer and a private consultant had put up a case that he had Temporal Lobe Epilepsy which impaired his decision making and his resposibility for his actions based on some very minor irregularities showing up occasioanlly in an electro-encephalogram. The jury bought that version, and he was confined in one of the state hospitals until "treated and fit for release". ( Despite that being a Neurological condition rather than a Psychiatric one even if he did have it.)
The irony was that, as a teenager, he would have gotten out sooner if he had just pleaded gulity, because he showed no symptoms in his years in hospital but couldn't be released until the Medical Superintendent coud sign declaration that his condition was effectively treated and he was safe to release - which he couldn't sign because there were no symptoms and no treatment available to offer. The state government in the end had to amend the law to allow the Parole Board to review Mental Health based confinements, and he was eventually released.
My contact with him was late in the process to discuss his seeking to be able to attend group sessions in the open ward, which was declined because he had sexually assaulted two psychotic women when he had been permitted to attend those sessions a year earlier. When I said "no" he grinned and said "Well it was worth a try!" (We got along well thereafter, and he never tried it on again. He was still there when I left.)