The absence of exploitation is indicated through consent,
no, it’s not. it’s exploitation by the barest definition, like exploiting a fallow field or a forest. the definition of exploitation can by synonymously defined as “use”. using a corpse is exploiting it. using a corpse which has, with informed consent, been consigned for use is still exploitation.
the barest definition is a synonym of “use”. the vegan society could clear up this ambiguity but they have chosen not to do so, and there is no reason to assume they prefer a special definition of exploitation.