Short answer in my experience: They will most likely remove it unless the person put time and effort into their review. One liners don't seem to last more than a few weeks, negative or not.
I'm not sure that bringing it to their attention will help much but I've had this happen to me recently as well. While we prefer to avoid customers who use yelp, I have setup a profile for our business and I respond to comments when I have time. My objective is to figure out how their system works as I believe that a lot of it is manipulated based on whether or not you use their advertising. I did respond to this person politely stating that our prices are based on market value, we offer a superior product, etc. About three weeks later his comment was moved to the filtered section although I doubt that my responding had anything to do with it.
There are other factors of course like the reviewers history, your current rating, even the IP that the post was made from.
I wish you luck. Yelp really sucks if you are the involved in the kind of business that depends on them. Extortion based advertising should not be legal.
