Master! You've posted again! I'm so happy to see you!
Anyways, I just want to start by saying that I feel really sorry for you, your cousin and your family. I'm not the biggest expert on this kind of stuff, but I remember a really distant relative of mine had a similar surgery. His chances were pretty low but he ended up the same way your cousin is. Your cousin is pretty much a vegetable, so I'm not sure if that's the best of luck but I guess he's lucky for not immediately dying mid-surgery.
Just to make sure, is this one of those situations where the person is basically in a coma and can be taken off of life support but there is a chance this person can recover from the coma?