So he has an incredibly poor quality of life and his "friend' wants to force him to continue suffering.
Some friend
He should be allowed his own freedom to humanely end his suffering.
I also notice that actually facing the underlying problem is not on the table, where is the medical research, where are the financial resources, where are the many people who would be needed to care for him 24/7 in perpetuity.
Instead of addressing the elephant in the room (either with support or euthanasia) society wants to force people to suffer.