I don't think BM used ACoC or not really has a point, first there's no way to tell what BM used or not used to begin with, since most of the fights are skipped; 2nd clearly ACoC isn't the only legit method of damage output for top tiers in the verse, BM can be using many other methods to achieve the same thing, like triple homie combo elemental attack, or lightning buffed sword swing with her monstrous strength, and non of them seem be to weaker than her ACoC.
I think the fact that BM can't put down Kidd and Law for this long, speaks enough, the details don't really matter that much here.