@wimpyegg
TBH I kind of understand why he doesn't want to be recognized as Zero. Remember, he, as Zero, already stopped a couple of alien invasions, the merman attack, some devils and assorted monsters
and the Apocalipse ( the angel he is fighting now was part of it ), besides more stuff that might have not have been mentioned already ... and that without any real counterpart or real recognition. If you read between the lines ,it is clear that he grew tired of having to fix all the problems of mankind by himself and that was a big part of why he decided to retire Zero ( that and the backlog of manga and anime he had accumulated
) ...
Given that, why would he show himself as Zero ( or Zero-like )? Wouldn't he be forced again to defend mankind alone of the end of the world of the month? Worse, wouldn't he be at odds with the current hero association and the World governement, that were already shown to be ... less that heroic and some of them also quite willing to take Zero down for good? That sounds like a hassle