Good overall, but is there justification for having consider_user_for_promotion called through a before_filter? It doesn't filter anything or redirect the request. It also doesn't retrieve instance variables for the request to process. You could theoretically put the whole method being refactored into a before_filter, but that's just a shell game.

I agree with making consider_user_for_promotion a standalone function. I like that because it is reusable, and self-comments the code.