There are two problems with bone. 1: Bone is more likely to become infect, and be rejected by the body. and 2: a lot of people want the option to remove them eventually if they used bone, the body may fuse them to the skull making removal impossible. Oh, and it'd be twice as expensive.
Honestly, I think its pretty cool that this dude had the balls to do what he wanted. Did he think this out all the way? Maybe, maybe not, but who's to judge? I just wish society could be more accepting of peoples life choices but hey, whatever.