We are just talking about it being literally a mode or not anyway which factually stands.
Do you think Hell Memories is a mode? I mean, hell memories also seems like a transformation and a satanic way where Sanji seems to have traces of a devil, and he has fire all over his body, like a sayajin.
That is not why I see Sanji fans consider hell memories to be a fighting mode, which Sanji can freely use, just to scale him higher in power levels.
But I see Zoro fans putting ashura as a mode, as if it were gear2, just to climb it in the skies, for reasons of power levels.
HM as well as Ashura are just demonic transformations that appear at the height of their respective struggles, and serve as a finisher. I would not consider this to be a mode of fighting.