Sadly, one of two things is currently happening:
1: The administration of the website rigidly enforces censorship by blocking entire posts, or replacing all the letters of certain words with asterisks (*). Fortunately the tw@s have not got to the concept of censoring the other ways of writing that kind of $hit.
2: The writer of the word is far too sensitive and twee to write the word "twat".
There are other examples (such as cvnt, fvck, and $hit) of legitimate alternatives to words that are commonly used to emphasize something, etc.
$hit, the tw@ has done it again.