Just because you're fine standing by your posts doesn't mean he is. If CNN didn't find him someone else could have and that's something he should remember in the future. It's not the main crux of the article or issue with CNN but it is a by-product that will affect the kid's life so that's why we're talking about it.
Yeah, that's fair enough. However, if CNN now came to me and said "you've been saying all these mean things, and unless you apologise, we'll write a long article about how you're a big mean racist Trump supporter", it wouldn't just be a question of whether or not I stand by my (largely satirical) shitposts. It would be a question of whether or not I want to be publicly shamed and defamed by a major "news" organisation.
There's no evidence that the redditor is fifteen.
It came from a 4chan dox, which is why I presented it as an allegation rather than anything else. It does seem to check out, and that's more evidence than Kaczynski's "oh no he is no kid no no no there was no blackmail just a friendly chat :) :) :)" tweet, but it certainly needs to be taken with the understanding that it could turn out to be completely and utterly false.
That said, CNN blackmailing an adult is only marginally less shit than CNN blackmailing a teenager. Hardly enough of a difference to matter.