I don't think the part about his quality of life is not important.

Lots of people have disabilities, only accounting for spina bifida which is physically less disabling that ALS, or muscle atrophy which leaves cognitive capacity intact, already puts them in the thousands. Someone needs to show them they can achieve many of what they dream about, because most of society only gives them pity and consent. We have Olympic Games for disabled people whose dreams are of being athletes, and we need people like Stephen Hawking to show disabled wannabe scientists and hackers (many of whom I believe read HN and ars) that they can also triumph in their geeky endeavours.