I will use the definition of "social justice" from wikipedia:

Classically, "justice" (especially corrective justice or distributive justice) referred to ensuring that individuals both fulfilled their societal roles, and received what was due from society. "Social justice" is generally used to refer to a set of institutions which will enable people to lead a fulfilling life and be active contributors to their community.

http://en.wikipedia.org/wiki/Social_justice

To me, a "social justice warrior" is an individual that is particularly concerned with the implementation of social justice. /r/TheRedPill is a forum devoted to discussing a variety of social justice. It greatly differs from the standard left-wing variety of social justice, but it is social justice nonetheless.

http://www.reddit.com/r/TheRedPill/comments/2lufno/women_dont_want_equal_treatment_they_want_special/

http://www.reddit.com/r/TheRedPill/comments/2ls5vq/successful_business_woman_doesnt_feel_like_a/

http://www.reddit.com/r/TheRedPill/comments/2luert/female_moderator_of_rpussypass_makes_post_to_talk/

http://www.reddit.com/r/TheRedPill/comments/2lskvf/from_september_to_october_2014_there_was_a_job/

http://www.reddit.com/r/TheRedPill/comments/2lsnde/in_their_own_words_dating_the_millenial_woman_is/

The linked threads are all critical of modern gender roles. They criticize the structure of society. In theory, TheRedPill is supposed to be about adapting to the world as it is, but often the threads on TheRedPill merely criticize the world as it is, and sometimes even suggest the way it should be. Furthermore, TheRedPill subscribers regularly venture into other subs and attempt to recruit venerable individuals to their cause. Last but not least, there is an abundance of anger on TheRedPill. Anger is a trait often a trait associated with many SJW groups.

Together, the above observations suggest that TheRedPill, in part, is an SJW forum. CMV.