The Darwin award is awarded to any who kill/sterilize themselves and are no longer in the gene pool. He “self selected,” as you say, to undertake this challenge. Copycatting doesn’t matter. If you are dumb enough to kill yourself in such a stupid way, for a challenge, whether adult or child, you are out of the gene pool and are thusly awarded a Darwin Award.
Certain kinds of deaths are too commonplace to qualify. And it has to be a spectacular example of one’s own removal from the gene pool by an otherwise mentally healthy and not typically “dumb” individual who has an atypical loss of reason. Thirteen years old is not an age of self-selection, to boot; children do not qualify ever.