This doesn't make sense to me. Kool-aid man is obviously a golem made from glass, crystal, diamond or transparent aluminum, something that can withstand impact with walls, though we can't rule out magical reinforcement.
The fluid inside him isn't used for biological processes, he is just carrying it around. If you empty him, he can just be refilled.
This seems like a pretty reasonable hypothesis. I see only one possible flaw. Golems are known for their extreme stupidity. Only being able to follow the literal meaning of restrictions and not talking. How does that fit into the Kool-aid man golem hypothesis? This is important we need to know.