There is no excuse for what this kid did, but I do feel sorry for kids like him in general that get sucked into this "famous" bullshit and don't grow up with a normal childhood. The way I look at it is not that much different from being a Hollywood child actor. It's like they are too young to understand what they are really getting themselves into sometimes. It also doesn't help that he had terrible, sleezy role models that just took advantage of him and his fame.
Still though, everything always narrows down to choices in life. Those were the choices he made and nobody forced him to do anything, so now he must face the consequences. All three of them should be ashamed of themselves, especially Keelan and the cousin- I expect more from 2 adults.