Interesting. Well, I am a dev and my company has both a free, lite version and a full, paid version of CraigsHarvest. And in the help and a few other places of the lite version we do highlight features that are available in the full version. I guess perhaps this could be another case of Apple being inconsistent with their application of the rules, although, based on the following clause from the standard agreement that I believe that rejection speaks to, I'm not sure that's the case. I'd have to know more details about that rejected app and how it was referencing those features.
Unfortunately the rejection notice does not reference any clause of the agreement. Basically the whole referencing unimplemented features thing is an unwritten (or worse, secret) rule.