Let's keep in mind that the original leak of Slave to the Rhythm isn't the original 1989 recording – it's a Tricky Stewart reproduction from the summer of 2010, of which the ENTIRE instrumental was reconstructed, that Michael never heard or signed off on. It's far from classic -- musically, it's a generic club track that is only listenable because of Michael's vocals and the lyrics. In truth, Justin's instrumental feels much more complete than Tricky's, whose felt like an amateur remix of sorts.
I've analyzed the statement as saying that the recording as a whole was unauthorized, meaning that Justin either unlawfully acquired the stem tapes and recorded his own "remix," or he was led to believe that the estate was giving him permission to.