If you are talking about the "Shintaro made Toumei Answer" thing, it was listed on his wiki page for a long time without a source. Since I couldn't find a source pointing to this being true, it can be assumed that it isn't canon and it has been removed from his page since. Though Shintaro does seem to be interested in creating music! In the first chapter of the Kagerou Daze manga, Shintaro is working on a song and he hopes that it'll be a hit on popular video sharing sites.