Hey man, I'm just fooling around, relax. If you wanna run a serious/realistic game (with the obvious exception of the protagonist's powers), no problem. I can certainly wait with shenanigans for later, or even drop them completely if you prefer that!
That said, an organism this size wouldn't really work like this, as far as I'm aware. Now, I'm no real expert by any means, but I'm doing a masters in biochem, and there are several non-trivial problems with 'Outside of very specific organs and muscles, all cells do everything'. But I'll save you the explanation, after all, that's not the point of the game, I think.
As for why a hivemind would need sound organs: sound is a very good way of transmitting information over long distances, so it could still very well use it. Unless this hivemind has psychic powers, of course, which I hope you'll agree has no basis in reality as we know it. And yes, that ear was grown artificially, but that doesn't take away from the fact that it's a much simpler thing than a working limb. I don't even really want a strict vuvuzela, an organ like this could work for amplifying sound, making communication over distance easier.
tl;dr: never mind my joke action, carry on.