It seems like there is little tactical payoff in doing this, as large, foreign militaries would already have detailed, accurate maps covering the whole world, China included. I bet this is an internal-resistance oriented policy.
Even then, if there were an internal-resistance movement that was well organized enough, they could get around this stuff. Seems more like it's there to keep some bureaucrats employed and possibly to prevent lone-wolf resistance 'fighters' who might not be well organized/smart enough to get around these measures.