The @user is being set to devise's current_user here in the parent class:
https://github.com/projecthydra/curate/blob/master/app/controllers/curation_concern/generic_works_controller.rb#L97

Once you are in the actor class, you don't have access to the current_user method anymore.  I think that's why they set the @user.

Now that I'm taking another look though, I realize that should probably be user instead of @user.  I'll see if I can change that.