This is evil. I have a mental illness and I have attempted suicide in the past. I can't think of much more evil than someone "assisting" me in that sad endeavor.
However, his argument is more consistent than that of most euthanasia advocates. He doesn't distinguish between physical pain and emotional pain. If we are to live or die based on "quality of life", then that ought to include everything, not just physical quality.
This is where the world is heading.