He's an individual. His life's his own. Providing he's not commiting crimes etc, what's the problem? And being 'his own person' could mean anything. Everyone's got the right to be the best they can, to be who they were meant to be.
Piercings, hair and clothes are all very personal to an individual. They want to style or dye their hair - big deal. Same with the other two. A person needs to express who he (or she) is. It's all about personal choice. Let him think for himself.