It technically makes sense that a "real" person would be omnipotent to a "fictional" person.
No... no, it really doesn't.
What can any of us do to the concept of Goku? Diddly squat, that's what. Dragon Ball is a ridiculously widespread and popular series, so Goku's everywhere, and there's no way any individual can "beat" him in any real way because there's too much material featuring him in existence and too many people who know him. The closest thing you can do to "beating" a fictional character in the real world would be to destroy their story and make sure nobody remembers them, but that's only really feasible in a totalitarian dictatorship and even they can't do much to things coming from
outside of that "bubble" where the dictator has control over everything.
There's pretty much only
one real person who can make any real change to a fictional character, and that's the one who's writing them. And even then, with Goku you've got the anime vs. manga (and even further division with Toyotaro doing Super manga rather than Toriyama himself) vs. video games vs. who knows what else. There's GT vs. Super, they can't
both be "the" continuation of the original series, so that's basically two different Gokus right there even disregarding differences in manga/anime/etc. Fictional characters outlive their creators pretty regularly (and outlive the creator's involvement even more often), sometimes they even keep getting new material after the (literal) death of the author, remakes and side-stories and so on.
Even omnipotent "this guy represents the author" characters aren't
actually the author themselves, just another character based on them... and just as fictional as any other in the series.
A real being isn't omnipotent relative to things that don't exist -- real and fictional beings are equally impotent against each other since neither can really do
anything to the other! They can only affect other beings that are just as "real" as them, not beings of a different "level" of reality.
Nice parody of ridiculous power level arguments.
