As someone who played this game way back on the ps3 I can give some context. The title is pretty on the nose as its Bayonetta's father after a big reveal and plot point. He's effectively the final boss of the game and part of a huge moment like you thought. The actual final boss is just some big monster type godlike figure, being more a spectacle than a boss really comparatively. It doesn't have much personal/plot connection and its right after this one so he would still be the penultimate boss regardless. You'd be surprised to know that the game itself has a lot of tracks kind of like this being that the game is centered around witches (bayonetta) and demons vs sages (balder/her father) and angels so almost all the boss tracks have that choir with similar intensity although not nearly as his theme since most of them are against heavenly forces.