He really hasn't been Byrne's Superman since right around 2000 and the Loeb/Kelly run. They tried to retcon huge chunks of Byrne's vision of Krypton. It just took a couple years until Man Of Steel got retconned away officially,although it's safe to say anything after and including EXILE is back in continuity after the merger in REBIRTH. at least on a surface level. If one goes in too deeply and scrutinizes the lose continuity threads left from taking Byrne's run out of the equation then it all unravels.