The Latin "Sic" is used as an abbreviation for the English sentence at the top of the page, or "this misspelling is intentional", or some such. Therefore the use of CategoryAbbreviation is valid, although prone to misinterpretation.
The category "CategoryAbbreviation" is intended to group together a certain kind of term people use in writing, so that people who do not already know what the term means or where it comes from have a starting point for finding out. "Sic" is alleged to be such a term, along with "e.g.", "viz" and suchlike; therefore it is the use of the word "abbreviation" in the category name which is problematic (since it does not include a wide enough range of terms) rather than the grouping of things like "Sic" and "e.g." with things like "TLA" and "SWMBO". I challenge the pedant to find a better word.