Exactly. It’s a tongue-in-cheek that basically says that you need to circumvent censorship when you want to talk about censorship.

By the way, I’m not a linguist and I just completely made up that usage of “atonal homophone”. Could an actual linguist chime in and tell us what’s the correct way to describe a “homophone” that doesn’t match in tone, in the context of a tonal language like Chinese?

It's usually still called a pun or homophone. Most puns in English don't precisely match phonetics (especially stress) either.