"rape is about power" doesn't mean "rape is motivated by an internal, subjectively felt motivation of desiring power" (although that may be and is often a component of the motivation).
in cases where the perp did not even know it happened, that is about power. they are capable of not knowing it happened overwhelmingly because of the conditions of social power that empower them and restrict the victim's agency, irrespective of their own personal sense of power. All rape is always about power, regardless of the individual rapist's motivations
I've written about the topic at length here:
https://immerautonom.noblogs.org/en-US/sex-desire-and-power/
and here:
https://immerautonom.noblogs.org/en-US/sex-desire-and-violence-ii/