I can understand why he wanted to end his life, and I can understand why his family thought it was the correct thing to do.
I think their decision was wrong because it was too soon after the accident to know whether he would be able to find a life that was worthwhile to him. I actually think it's very likely that with some time he would have because I have met people who have been there and done that, and several years later see their life as actually better than it was pre-accident.
So many people on here saying 'can you imagine how awful that existence must be?' Well yes, but I have also met people in his position who have a life (not existence) that is every bit as good as mine. And if you gave them back the use of their body it wouldn't suddenly become a 'better' life (although no doubt it would be an easier one).
If I had a friend who wanted to commit suicide because of some external trigger - whether it was because of accident, or loss of money, or loss of a loved one, or because they just couldn't see any value in their life I wouldn't say to any of them "yep you're right you know you can't possibly ever have a life that was every bit as good as your old one". Because in no cases would that be true. They might not, but in every case they would have a chance of having a good life without money, without a loved one, even without the use of their body.
Most people never get close enough to very severely disabled people to understand that their life is often equally good as those of the able bodied. It really is. Equally good. So they don't have the confidence to say to someone such as this man "you might not be able to imagine it now, but I can tell you, that your chance of a happy fulfilled life is the same as it was before the accident" (after all how many able bodied people do you know, with no major issues who are utterly miserable- I can name a few- health and wealth don't guarantee happiness). BUt that is the truth. Unfortunately with a very severe injury it is likely to be a shortened life, but for a young man the chances are it could have been a full one. I don't think he could have realised that in such a short time though.
I'm really not judging him or his family, I feel terribly sad that they were helped in this way, when I think better help could have been provided by meeting people who had been where he was but had gone onto live happy full lives.
I do think there maybe a place for assisted suicide when someone is terminally ill. I think for anything else (including dementia) we could end up judging a person's life as being valuable or not, and that to me is dodgy ground.
I speak as someone who spent 6 years of my son's life assuming that he couldn't possibly have full value or enjoyment in his life unless he was somehow 'fixed'. I was totally and utterly wrong.