They'd still have to rollback account data. You can't have all these users who obtained the MSPP/SuAP/BGC avatars from duped items out there.
I really don't care what they do but all signs point to them manually fixing the problem vs just rolling back.
There's no way to say what will and will not be affected by a rollback, it all depends on how their databases are structured. If they store a users unlocked avatars as a single string or array as a column in the users table, then yes, most account data would be rolled back. However, if they store a users unlocked avatars in a separate table, then account data would be safe.
You can roll back separate database tables, so it all depends on how they store their data.
You would need to know exactly how their database(s) are structured in order to make any calls like this.