It is the same old story: censors are generally overworked and from a particular community, so figuring out the intended meaning of a message in another community is usually done using surface characteristics. To do a "deep packet inspection" figuring out what a meme really means takes time and effort, so it is only done when it seems necessary. This is why there is so much satirical sf from the Eastern Block - as long as the setting was the US, you could joke about bureaucracy, lack of freedom and shortages.