I don’t think your premise is correct. From memory, and scanning a couple episodes illegally uploaded to YouTube, it doesn’t look like Captain Planet flies away at the end. Usually, the scene just transitions to later after he’s gone, but the few times we see it, he dissolves into light, presumably returning the rings powers to the planeteers and disincorporating. He doesn’t go anywhere, he bodily ceases to be.

Where does his mind go? I think he’s a spirit. Where does team spirit go after the football game is over and everyone goes to bed? It still exists, but it’s not… here. It has to be activated to be tangible.

Just let anyone scrape it all for any reason. It’s science. Let it be free.