No sources on this, though, only a couple articles from around the time of his death stating it as it was a fact already.
In all this time, and with all this fuzz, none of the actual authors of RSS, which are still alive, have come clear about this.
Disclaimer for immature people: This is not meant to disrespect Aaron's memory and/or legacy.
I also wrote a piece of software that went super viral among sysadmins all over the city and I was getting "thank you" emails for years after.
Had anyone been developing RSS spec next to me I'd definitely jump on it. As any 14 y/o would.
I don't think I'm particularly brilliant or even smart. Your circle defines you.
Surround any healthy teenager with interest in tech with the right people and they'll have a lot to show in no time