Apparently, the rating body is only able to accommodate game publishers’ confidentiality requests while submitted games are undergoing review. The moment a decision is reached (whether it be an approved rating or rejection), the GRAC is legally obligated, without exception, to make it public through its official website and the digital government gazette.
They could avoid it, if they released the games at a later time than the rest of the world. But I do not think that its worth it.