I'm glad you said, "He", when you mentioned 'they' in first post I was wondering if there was more than one friend.
I did know the law permitted assisted suicide had been passed in Canada but this is the first time I have heard of someone actually contemplating it.
He is able to fly to Canada, I would have thought that indicated he was capable of committing suicide without assistance. I am in no way advocating suicide but there is, to me, something unwholesome about people being employed to kill others or help them kill themselves.
If your friend has his heart set on this and has been approved for it, there is not much you can do. Whether he actually goes through with it remains to be seen.
It's very sad that he feels this way when there is so much help available now to make remaining life comfortable and even worthwhile. The hospice movement is marvellous with this.
More help should be available for the terminally ill. Nobody has to die in pain and distress.
I'm truly sorry for your friend, something has gone seriously wrong with his care for him to contemplate this solution. People in my family in similar circumstances died naturally, just didn't wake up, and knew they were loved, well cared for and supported right to the end by their loved ones, as well as a good medical team who prescribed adequate pain relief.