the inf power

will be dangerous in humans world

Kirby is literally implied to be related to an eldritch god and defeat planet busters and godlike beings on a daily basis. That and he canonically has infinite power. All for One is nothing compared to Star Dream, Galacta Knight, Void Termina, etc… in term of raw power. Kirby would probably see their fight as a game at most unless AFO start destroying Dreamland, that's when Kirby would destroy his body before obliterating his soul as he usually do.

The Kirby universe is trully a magical place when even the butterfly seen in most Kirby intros is stronger than AFO. Yes this butterfly is described as the equivalent of the grim reaper in the Kirby universe.