As an minor amputee (missing little finger right hand, right hand ring finger don't work worth a darn) I can tell you that after a while you learn to laugh about it and joke in the way that we, as friends, joke about things. But at this point in his life, and probably for the next year or two, the shark bite victim will be going through a lot of ups and downs emotionally. If spinning Poi is what he focuses on to help his therepy (and there will be LOTS of physical therepy) then god bless him for having something to focus on.
I remember after my accident I spent 18 days in the hospital having 5 surgeries (and 2 more after I got out of the hospital). One day stands out in my mind. I was doing hydro-therepy (basically learning to move my hand muscles again while it's immersed in a whirlpool to help ease the pain) I'm a guitar player and use to be a piano player. That day in hydro-therepy I was able (finally!) to touch my thumb and first finger together. At that moment I knew that I would once again be able to hold a guitar pick. I broke down crying right there because I knew that my life would go on, modified, but with the same passion for music that I always had.
So if spinning fire is what this man can latch onto as his focus point, then I wish him all the luck in the world. That's what's going to help him get through the pain and frustration of learning to live his life again.