Who says he "made it for" children, anyway? I would imagine that he made it, because he thought it was a game that he'd like to play himself. If he made it "for" anyone, that's probably who it's for. That it appeals to children of all ages, from nine to ninety-nine, is just a sign of good game design.
If men above the age of 40 weren't allowed to write and illustrate children's books, we wouldn't have classics like The Cat in the Hat and How the Grinch Stole Christmas. Yep, I'm talking about Dr. Seuss.
So explain how a man above the age of 30 making a game for all ages is any different.