Because of this.
The metaphor of rape seems peculiarly attractive to male post-colonial writers. What happens, one may ask, when the literally colonized woman tries to speak, if her place has been usurped by the cross-dressing colonized (and that only metaphorically) writer who has invaded and appropriated the margin by relegating woman to a metaphoric status (not a new phenomenon, to be sure, but more disturbing, I would argue, when it results in depriving her of a reality specific to her lived experience).
Sylvia Soderlind, "Margins and Metaphors: the Politics of Post-***", in Theo D'Haen and Hans Bertens (eds.), Liminal Postmodernisms, 1994