Yes, it is not a mistake. Maps can be “illegal”. That is, only in countries that have in place a licensing regime – such as China. The aim is to remove from the web maps that have “political mistakes” (I presume it refers mainly to representation of borders and “territories”) and those that disclose State secrets (I remember this rule from the old communist country of my origin, where city maps had big holes where the industrial zones were located). Well, that’s one way to achieve consistency in mapping data across the whole country, just hope no one will have similar ideas in Australia!
What’s really interesting, are statistics quoted by the Chinese State Bureau of Surveying and Mapping: it “…uncovered 1,058 cases of illegal mapping services, including more than 30 relating to foreign organisations and military”, “…3,686 websites out of 41,670 web mapping service websites were found to contain political mistakes, and more than 200 websites were closed”. Mapping must be quite popular there, but that’s China. I wonder what would be the numbers for Australia (total websites of course, not closures!).
On a related topic, Chinese government is not the only one censoring online content. Google created this interesting map that shows world wide statistics about “Government requests directed to Google and YouTube” to remove content from services, or provide information about users of services and products.