First of all, I'm not trying to sound defensive here: (I want to discuss this solely for the sake and enjoyment of discussing things)
But it's because it's more than just "Manato is dead - yeah it's tragic" that they used the music in the first place. Manato was literally declared dead ~0,5-1 minute before that and that rather short musical scene showed us the funeral. I don't understand what's the big dealbreaker here? Isn't that the 1x1 of making movies or TV shows? You use music, sound, the camera etc. to make things more tragic, to appeal to the audience and enhance the effect.The musical scenes are unnecessary because most of them don't give any new content. They just emphasize or reiterate what we already know. For example, Manato is dead. Yeah it's tragic. Then we get a minute or more of musical moping after that.
Same thing when they gave him his badge - in fact that scene in particular was nothing but the ED of that episode in general and that's really a rather common thing to do, right? (and for a reason)