The easiest way to see if an image is sexualized is to see whether there are any clearly defined sexual characteristics in the image. This includes, but is not limited to, nipple buds, cameltoes, overly bulging breasts or buttocks, and provocative poses. To an extent, this includes males as well, but by its nature is far rarer.
This BG image contains none of that, it's just some children. If you think it's dirty, it's because you're a hypocrite who spends too much time guiltily browsing "nothing" on google. It's a bit of an incredible stretch to claim that any of them are in provocative poses, as well.
The map itself is boring, with no interesting content whatsoever, but that doesn't make it unrankable.