I think it's due largely to naturally disciplined calculations skills, so if you want to call that tactics, I guess it is. I think they automatically don't have to learn how to slow down and pay attention to important parts of the position. Most of us approach the game as beginners wanting to move some pieces around and make meaningless threats, and end up playing a4 Ra3 or similar crap. I don't think young kids who show talent and get coaching deal with these types of hazards at all, and other class player pitfalls such as not looking for a strong response from the opponent. I think for whatever reason they're drawn to look at important aspects in the position from the beginning, and naturally try to find strong replies from the opponent. So from day 1 they're spending their energy on refining good play and so it's no surprise that within a year or two they're 1st category players, and within a few years after that (and with some work) are masters.
I don't think openings have anything to do with it, although obviously with a good coach they can have quite an extensive opening repertoire.
I think once anyone starts to have a more disciplined way of looking at the board they're very close to the 1st category player rank. The problem for most of us is by this time we have to unlearn a few years of bad habits we picked up along the way. Plus at such a young age it's easier to absorb information, so that's how you get young masters.
9 is pretty young though. If the rating is fake, then it will be known soon enough as the kid continues to play. If he's half as good as his rating though (lets say at least 1st category) then he'll be master strength soon anyway. If they want to put his name as youngest ever then maybe some investigation is required first. It wouldn't be the first time false tourney results were turned in to boost rating points.
Today on Chess.com/tv we talked about the new 9 year old "youngest" master. See article here: http://asbarez.com/90237/samuel-sevian-youngest-us-chess-master-ever/
Two Questions:
1. At this age, to what extent--if at all--do these kid prodigys know and memorize openings?
a. Is the real secret to their rating their tactical OTB, figuring it out for themselves, play?
b. What about for an accomplished junior in U12 training with GMs? How deep is the opening prep, knowledge of varied openings, and ability to say "hey, that's a Chigorin defense"
2. 9 year old master? Is this a B.S. rigged set of games by the local club tourney director? Suspicious abounded based on the point jumps this kid had.
a. if so, do we care? It's USCF and not FIDE.
b. Is FIDE euro trash? :)