What i think is that this is incredibly complicated for all the wrong reasons.
Adam had what they called a mental illness, which is just a (false) label, he was not suffering from depression or a psychological illness he had a physical condition caused by the brain. Much like we would not call a brain tumour a mental illness pain caused by a malfunctioning brain is not mental illness. Its also an invisible condition which makes things harder to see clearly.
He should have been allowed to end his life legally. The current Canadian legislation is idealized 1970s values passed into law in 2016.
Medicine does have a long way to go, modern medicine is only now beginning to get to an advanced level, we know much more compared to just 100 years ago but the adage half of what you learn in medical school will later be proven wrong is probably still very true today
As for the people who wanted to commit suicide but changed their minds, having a sense of control over one's life and destiny is important for all humans, we all want to be have control instead of being controlled. Its a sidetrack from the real issues.
When it comes to actual mental illnesses we are wedded to the biochemical crap (backed up by bad path dependent medicine and drug company money) claiming depression and anxiety and so on are caused by "biochemical imbalances" hence need to be treated with drugs that are a solution looking for a problem (uppers). And in situations where they don't work (because they are based on lies) some victims want to (understandably) commit suicide. Instead we need to accept that uppers can chase symptoms away at best and if it fails its not because the problem is untreatable but because modern medicine has fallen victim to the streetlight effect. Drugs are not the answer to psychological problems, counseling is, and not the CBT crap which is a step beyond Freud which makes sense for robots stuck in a feedback loop, not humans who have lost hope, are lonely or have suffered from abandonment or abuse.
This better treatment is available but more complicated and harder to access. It needs to be very personalized and costs more (upfront, its actually cheaper long term).
I don't support legalized suicide for mental illness because we are treating it incorrectly. In principle everyone should have the right to end their life if they wish but lying to people, giving them sham treatments leading them believe they can't be helped and then kill themselves is unacceptable. If we admitted the truth and made proper treatment widely available and people with mental illness still wish to end their lives i would be more supportive but its still tricky because in general proper treatment would help patients find the hope and happiness to live but counseling is not a take a drug and feel "better", its a process and it can take time and going to many counselors to find the person a client bonds with (and some people give up very prematurely, the first counselor doesn't work out, so they refuse to seek out another). As someone once said (paraphrased) treating despair is not about the chemistry of drugs but about the chemistry of human relationships.