I get what you're asking. I've wondered about the same thing myself quite a bit, and I'm still not sure that I know the answer, but I'm going to tell you what I think anyway - lucky you!
Jesus had a way of asking people if they wanted to be healed:
that always seemed a little funny to me; as if why bother even asking - Yeah, he wants to be healed! What do you think? It felt like a silly formality and I would even feel a little resentful - like I was wasting my time by having to read it. As a Christian, I believe that everything that is in the bible, is in the bible for a reason, but for the life of me I couldn't figure out why this was necessary. It took me a long time to realize that maybe this man did not want to be healed. Thirty-eight years; that's a long time. A long time to be relying on charity. A long time to not have to have a job, a skill, responsibility or expectations placed on you. A long time to learn that your affliction is actually your greatest assert. Should Jesus decide to heal that man, in an instant his life would be changed. Everything he knew, the means of his survival and everything he thought about himself that very moment would be gone. Surly Jesus knew this man's heart, but did this man know his own?
Bo, check out your Facebook, I can promise you that you'll find friends on there who don't want to be healed. People who, aware of it or not, are simply not happy unless they have something to fuss about. Some people just don't know to relate to the world without a sob story.
Now I certainly don't mean to imply that your friend does not wish to recover, but one thing I've noticed about prayer is that through the act of forcing myself to bring my requests to him, I kind of have to strip away all the bologna that I can employ in speaking to others or in my own head about what and why I want/need/desire something. Because he already knows, I have to be honest with him and therefore honest with myself. I do not understand the mind of God, so I cannot say with certainty that he has not resolved, for whatever reason, to heal a person
if prayers are said on their behalf. I don't know. I do know that prayers of petition require faith
and as Christians the act of relying on faith is beneficial to us. Maybe that's why he want's us to do so. We pray, as an act of obedience, because we are instructed to, but I think the benefit is far more ours than his.
Anyway, that's what I think.
Edited to say: I'm really sorry about your friend Bo, and for what it's worth; I'll be praying for him as well - and you.