The other side's whole case rests on an absence: Saitama has no shown ceiling, so Goku supposedly can't prove he exceeds it. But that's not a win condition, it's a blank check. Fair enough, Saitama has never been pushed. Still, Goku has actual concrete paths to victory: superior combat speed, instant transmission, ranged energy attacks, and adapting under real pressure. Saitama's best showings are gag one-shots against opponents who never test him. Narrative potential isn't a feat. If we judge by demonstrated ability, Goku can win.