If you haven't read what he wrote on assisted suicide, it can be found here
The part at the beginning is just the reporter's commentary, the actual stuff by Pratchett starts a few paragraphs in.
How can anyone read this and still claim the sanctity of life trumps a person's desire to end it before the end?
(The cynic in me also says that as a well known atheist, we'll be hammered with deathbed conversion stories about him. In fact, they've already started.)