>>96205986>The point of that episode was to transfer ownership of the dimensional scissors to Marco. The action movie sexual tension between Future Marco and Hekapoo, and Star drooling over Future Marco's abs were just gags not meant to be looked into so much. Marco and Hekapoo are onscreen together again in "Face the Music" and don't acknowledge each other at all.
I think the thing you need to understand is that this is a big existential thing that's been a philosophical discussion for centuries. Not just that but the numbers they used were big, but only big in a human scale. If they said it took him a thousand years that's beyond what humans can fathom so it woldn't matter, and if they said it only took a few years it wouldn't really be a big deal and easy to overlook, but sixteen years is harder for people to overlook since it's a number people can process and understand it as being large at any phase in a person's life.
Not only that, but the episode made it look like Marco didn't just sit there or do random shit, he had an actual LIFE. He had a pet, he learned things and had an education, he developed skills that would put him WAY beyond a strip mall green belt. The ending didn't really wind up being much of a gag either, since it had this melancholy tone that made it clear this was something the character was thining about instead of a one off gag to move past. If he came back and immediatley fawned over Jackie like normal or signalled nothing really changed, it'd have been a very different reception from the episode we actually got.