The Relativist position is more of a philosophical position, in which the person believes that all cultural practices are non-oppressive and/or not morally wrong. All cultural practices must be looked at from a view of difference, rather than on a better-worse scale. Only individuals within the group that practices the culture they do can judge the internal functions of their culture. Feminism in general is a political movement, which posits certain things that happen in society towards the genders are morally wrong, and should be changed through cultural engineering and public policy. Feminist psychology is the psychological extremity of feminism, analyzing how gender and sex play into the methodology, practice, and results of psychological experiments and studies. Because feminist psychology passes judgement on cultural and scientific practices as either "good" or "bad" from a moral or ethical standpoint, they do not follow the relativist doctrine.
I believe Psychologists should hold a anti-relativist position. From a practice standpoint I think it is imperative they have a relativistic position when doing research because of the biases that can show if they believe someone is more morally righteous than someone else. Making moral judgements is not in the nature of psychology, studying human behaviour is. If psychologists want to be politically active outside of their profession I think that is fine.