Say a player was sent hunting for Pokémon at a beach in Sanya and were to then upload images from the game to the internet. This would be perfectly harmless, unless that area happens to be the location of a well-hidden military base that is not shown on Chinese mapping systems.
If players were shooed away from where they are not supposed to be, this info could be relayed to Niantic, the American company behind Pokémon Go. Game developers could look for areas where lots of Pokémon were spawning, but none were being caught, and would then be able to draw some problematic conclusions.