I think the audience is 20, but not strictly solely 20. The audience scope is much MUCH bigger than some block of 20 - 25. They are not the only ones playing Fortnite and that's why I dislike the example. That's like saying I want to use Pokemon to target 10 - 15 year olds but it's entirely dismissive of the older audience that actually is playing the game.
Basically, I completely understand what Yoshi P is trying to say, but I think his example was incorrectly and ignorantly used. That's about it really. Nevermind the fact that we're using a 4 year old article to make a point like it has any relevancy today.