It is impossible to generalize and claim that popular media is harmful to social activism. Popular media can be used for purposes that benefit society. For example, there are many fundraising efforts for good causes that are promoted through media and that reach many more people than they would through traditional means.
From what I understand it's a movie about these rappers lives. I don't think they're the best influence and should not be admired or looked up to. I haven't seen the movie but I know about these rappers and their music. The music doesn't send out a positive message at all.
I would say that using this particular example is very loaded and slanted. By relating the lifestyle and politics from Straight Outta Compton (based on activities from 25 years ago) directly to contemporary lifestyles is dangerous because it does not clearly address the issues of our times. While these issues still exist, we need to claim contemporary perspectives to our causes.
I believe that this movie, Straight Outta Compton is just a movie and really isn't going to effect anything such as social activism or anything of the such. If anyone lets it effect them, why don't they just look away. After all, it's a movie. In the reality of things, it's unlikely for a movie to effect the way the world works.