Make the scout have a full drums set and make the medic have either an electric guitar or violin and make the pyro have a piano since he already has a taunt with one and also there is a drum and a electric guitar taunt in the game makeing scout's and medic's reasonable.

I thing that's the reason the developer isn't adding it because the melody sounds goofy and it has bugs so he things it will take forever for him to fix it. Like the bot crisis don't give up be persistent and keep upgrading this taunt people already like it so you only have to convince the developer.