An interesting debate going on here, with your host playing Devil's advocate.
So, what level of misery is it where we decide that a person's life is no longer worth living, that killing them is doing them a favor?...I honestly haven't made up my mind on the case in question, nor do I think I ever will (to my own satisfaction), simply because I've never been in the situation discussed (that situation being the British case of Andrew Wragg).
It's a horrible thing to watch someone you love suffer. It's even more horrible when it is a heavy burden of responsibility on your own shoulders, as with a parent and child. Worse, though, is to murder your own son and call it mercy.
So far, the opposition ranges from snap judgments of Mr. Wragg's motive followed by angry condemnation, to thoughtful views on the nature of life and the responsibility of the living. Feel free to add your own thoughts.